1/30/2024
Science Chemistry Elements & Sources
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Chemical elements are the basic building blocks of matter. They are substances that cannot be broken down into other substances by chemical reactions. The basic particle that constitutes a chemical element is the atom.
Chemical elements are identified by the number of protons in the nuclei of their atoms, known as the element's atomic number. For example, oxygen has an atomic number of 8, meaning that each oxygen atom has 8 protons in its nucleus.
As of 2024, there are 118 chemical elements that have been identified. These elements are organized in the periodic table, which is a tabular arrangement of the elements by their chemical properties. The periodic table summarizes various properties of the elements, allowing chemists to derive relationships between them and to make predictions about compounds and potential new ones.
Here are a few examples of elements:
1. Hydrogen (H): The lightest element, often associated with water.
2. Helium (He): A noble gas named after the Greek word for 'sun'.
3. Carbon (C): An essential element for life, known from coal and diamonds.
4. Oxygen (O): A vital element for life, forming part of the air we breathe.
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1. Hydrogen - About Hydrogen: Hydrogen, the universe’s most basic and abundant element, accounts for approximately 90% of the universe’s mass. It also holds the third position in terms of prevalence on Earth, representing about 15% of all atoms. As the element with the least weight, hydrogen, when ignited in air, results in water as the sole residue. This characteristic has led to the proposition that hydrogen could potentially serve as a substitute for fossil fuels in our energy system.
However, despite its omnipresence, the most straightforward methods of obtaining hydrogen on Earth are steam reforming of natural gas or electrolysis of water. To date, these methods have not proven economically viable for generating hydrogen as an energy source due to the high cost of input and the relatively low benefit derived.
The history of hydrogen’s discovery is a complex and lengthy one, with numerous scientists laying claim to the honor. Robert Boyle, an English physicist and chemist, is likely the first to have isolated the element in 1671, although the concept of ‘elements’ was not yet understood. By 1766, another English physicist and chemist, Henry Cavendish, had accurately characterized hydrogen’s properties. However, it was not until 1807, when John Dalton proposed his ‘atomic theory,’ that the idea of ‘distinct elements’ emerged. Cavendish is generally recognized as the discoverer of hydrogen.
Hydrogen, in its raw form, is primarily utilized near its production site. Its two main applications include fossil fuel processing and the production of ammonia for fertilizers. Hydrogen gas has been employed as a foundation for lighter-than-air transport. Numerous laboratory and common household acids and alcohols are composed of hydrogen compounds. Liquid hydrogen can function as a superconductor and, when combined with liquid oxygen, forms a primary component of rocket fuel. The hydrogenation of unsaturated oils yields fats for edible products. The range of applications that involve hydrogen is vast.
Three known isotopes of hydrogen exist. The most common is the single proton of 1H, or protium, which can be viewed as the fundamental building block of the universe. The addition of one neutron to protium results in a less common form of 2H, Hydrogen-2, known as deuterium (D). Deuterium is a natural component of the Earth’s oceans; water artificially enriched with deuterium is termed “heavy water.” While both protium and deuterium are stable isotopes, 3H (tritium) is radioactive and is frequently used as a tracer in scientific and industrial systems, as it can be easily detected when it emits radiation. Large quantities of tritium are produced in and for laboratory settings.
Natural sources of hydrogen encompass degassing of deep hydrogen from Earth’s crust and mantle, the reaction of water with ultrabasic rocks (serpentinisation), water in contact with reducing agents in Earth’s mantle, weathering - water in contact with freshly exposed rock surfaces, and the decomposition of hydroxyl ions in the structure of minerals.
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2. Lithium - About Lithium: Lithium, the lightest alkali metal and the third element on the periodic table, is unique in its properties. It is less dense than all elements except for helium and hydrogen, and it is one of the few elements that can float on water. Lithium is distinguished by its high specific heat and electrochemical potential, and it is the only light element capable of producing net energy through nuclear fission.
Despite its reactivity, lithium does not exist in its elemental form naturally on Earth. It was one of the first three elements synthesized during the big bang and is found in stars. On Earth, lithium is found in specific minerals, and its ions are present in seawater, mineral springs, clays, and brines. The element was first discovered by Johan August Arvedson in 1807 in a petalite sample, and its name is derived from the Greek word for “stone,” lithos.
Lithium is most well-known for its use in high-performance, rechargeable lithium-ion batteries, which power electric vehicles, electronics, and smartphones. These batteries generate energy through the movement of lithium ions from a negative anode to a positive cathode, separated by an electrolyte solution of lithium salts. Due to safety concerns about overheating, research is being conducted into alternative electrode materials to make these batteries more efficient, longer-lasting, and cost-effective.
In addition to battery technologies, lithium has numerous other applications. Its high specific heat makes it useful in heat transfer applications and as a strengthening agent in lightweight high-performance alloys. Lithium compounds are used in air purification, industrial desiccation, and as components of soaps, fireworks, and welding fluxes. Lithium also has uses in military and defense, optoelectronics, and biomedical and organic chemistry. Despite having no inherent biological function in the human body, lithium carbonate is a key component of mood-stabilizing pharmaceuticals for the treatment of bipolar disorder.
Lithium is primarily mined from ores of petalite (LiAl(Si2O5)2), lepidolite K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2, spodumene LiAl(SiO3)2 and also subsurface brines. Australia and Chile are the world’s largest producers of lithium.
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3. Sodium - About Sodium: Sodium, a member of the alkali metal group, is a conductive metal with a silvery-white hue that’s soft enough to be cut with a knife. It’s less reactive than potassium but rapidly oxidizes when exposed to air and ignites upon contact with water, releasing hydrogen and sodium hydroxide. This metal, which shares the unique property of floating on water with only potassium and lithium, is the most commercially significant alkali metal and the sixth most abundant element on earth. It’s found in salt mines, seawater, and various minerals like cryolite, feldspars, sodalite, halite, natron, and zeolites. Sodium is typically produced through the electrolysis of a molten mixture of sodium chloride and calcium chloride in a Down’s cell.
The element was first isolated in 1807 by Sir Humphry Davy through the electrolysis of sodium hydroxide, a method he had used just months before to isolate potassium. The name “sodium” comes from “soda,” the common name for sodium carbonate, which is derived from the Arabic word “suda” or Latin “sodanum,” both meaning “headache.” This is a nod to the compound’s long-known headache-relieving properties. The Latin term for the compound, “natrium,” is the origin of sodium’s elemental symbol, Na.
Sodium has a wide array of applications in the industrial, biomedical, and chemical sectors. Metallic sodium is primarily used in chemical reactions to produce organic esters and compounds like sodium azide, indigo, and triphenylphosphine. It’s often used in nuclear reactors due to its low boiling point. The distinct yellow-orange flame produced by burning sodium is what gives street lamps their unique color. Sodium compounds, which are highly soluble, are frequently used in soaps, glass products, papers, and textiles. Sodium chloride, also known as table salt, is a common de-icing agent. Sodium is vital to the functioning of most systems in the human body and is commonly found in food additives and pharmaceuticals.
Sodium can enhance the structural properties of certain alloys like aluminum silicon and tin nickel copper. Sodium potassium alloy (NaK) is particularly effective as a heat transfer medium and a desiccant. An alloy of sodium, potassium, and cesium (Na 12%/K 47%/Cs 41%) has the lowest melting point of any known alloy. Sodium has found new uses in high-tech electronics and optics: sodium yttrium fluoride (NaYF) is a luminescent phosphor nanocrystal used in LEDs, sodium bismuthate has been studied as a 3D graphene analog, and sodium-air batteries are a promising next-generation green storage medium with the potential to rival current lithium-ion battery technology.
Sodium: Most sodium is obtained by electrolysis of molten mineral sodium chloride (halite). It occurs in many other minerals as well, including amphibole, zeolite and cryolite. Halite is mined in the USA, China, Germany, Russia and Canada.
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4. Potassium - About Potassium: Potassium, a member of the alkali metal family, is the seventh most abundant element on earth, accounting for 2.4% of its mass. It’s found in seawater, most soils, and minerals like orthoclase, sylvite, carnallite, kainite, and langbeinite. As a typical alkali metal, potassium is a waxy solid that’s soft enough to be cut with a knife. It starts off with a silvery appearance but quickly darkens when exposed to air due to oxidation. It’s highly reactive, exploding violently upon contact with water and rapidly converting to potassium hydroxide while releasing hydrogen gas. Potassium is the second least dense solid element at room temperature, just behind lithium, and it’s one of only three elements (along with sodium and lithium) that can float on hydrocarbon-based mineral oil. Despite being non-toxic, potassium is classified as hazardous due to its dangerous reaction with water. Naturally occurring potassium consists of three isotopes, two stable and one radioactive, making it the most common radioactive element in the human body.
Potash (potassium carbonate) has been used by humans for centuries in glass, soaps, and other applications. It was obtained by leaching wood ashes. In 1807, Sir Humphry Davy isolated metallic potassium from molten potassium hydroxide (caustic potash) using electrolysis. The element’s name, “potassium,” comes from “potash,” and its elemental symbol, “K,” comes from the neo-Latin “kalium” and the Arabic “al-qalyah” or “qali,” all meaning “alkali.” Today, pure potassium metal is often produced through a similar electrolytic reaction involving sodium metal and potassium chloride. Potassium compounds, such as potassium chloride (often referred to as potash, muriate of potash, or MOP in the mineral industry), hydroxide, nitrate, carbonate, chloride, bromide, iodide, and sulfate, are abundant and easily extracted from deposits in ancient lakes and seabeds. These compounds are highly soluble and are used in many soaps and detergents, glass and ceramic glazes, stains, and dyes. Potassium nitrate is used in gunpowder and pyrotechnics to produce a violet color in fireworks. High-purity potassium compounds have numerous applications in pharmacology, medicine, and electronics. Alloys of sodium and potassium are useful as heat transfer mediums, desiccants, reducing agents, and can be used in nuclear reactors.
Potassium is vital to life. The uptake of potassium ions is a key mechanism in the human body, and potassium compounds are important dietary components. They can be used in food additives such as baking powder (potassium sodium tartrate) and low-sodium salt substitutes. Plants use soil-based potassium as a nutrient, and one of the main commercial uses of potassium compounds, such as chloride, sulfate, and nitrate, is in the production of fertilizers.
Experiments with potassium have revealed several potentially useful applications for the element in high technology. Potassium-ion batteries, an experimental design based on lithium-ion technology, substitute potassium ions for lithium ions and have shown to retain charge after nearly 40 times more cycles than a similar lithium-ion model. Researchers have created a negative temperature system by cooling potassium gas to one billionth of a degree below absolute zero, a remarkable achievement that could allow for further study of quantum effects in practical applications such as superconductivity.
Potassium: Potassium is obtained from evaporite salt deposits containing sylvite (potassium chloride). It is also obtained from the minerals alunite and carnallite. Orthoclase feldspar is a very common potassium-bearing mineral.
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5. Rubidium - About Rubidium: Rubidium, together with cesium, belongs to the group of the heaviest nonradioactive alkali metals. These elements are highly electropositive and extremely reactive, igniting upon contact with air or water. Despite their minimal toxicity, their reactivity classifies them as hazardous substances. Both are soft and ductile solids. While cesium is liquid at room temperature, rubidium remains a silvery-white solid until it reaches its melting point at 39.3 oC.
Rubidium was discovered by Robert Bunsen and Gustav Kirchhoff in 1861, shortly after they identified cesium as a new element using flame spectroscopy. They were examining the mineral lepidolite at the time. The name “rubidium” comes from the Latin word “rubidus,” meaning “dark red,” which refers to the vibrant color of lines in its emission spectra.
Rubidium is more abundant in the earth’s crust than initially thought, now considered the 16th most abundant element. It is found in minerals such as lepidolite (its primary commercial source), leucite, pollucite, carnallite, and zinnwaldite, as well as some potassium minerals and brines. Natural rubidium consists of one stable isotope (85Rb) and one radioactive isotope (87Rb) in a 72.2 to 27.8 ratio. The decay of 87Rb to 87Sr, with a half-life of 49 billion years, serves as the basis for a rock and mineral dating method.
Rubidium has various medical applications, including the use of rubidium chloride as a biomarker and radioactive 82sup>Rb for detecting brain tumors. Rubidium compounds are used in photoelectric cells and optical glass components, as catalysts and “getters” in vacuum tubes, and to produce the color purple in fireworks. Vaporized rubidium is often used in laser cooling and Bose-Einstein condensation, as its spectral absorption range aligns with many commercially available laser diodes. Like cesium, rubidium is also used in highly accurate atomic clocks that form the standards for GPS and telecommunication networks.
Rubidium: Although rubidium is more abundant in the earth’s crust than copper, lead, or zinc, it forms no minerals of its own, and is, or has been, produced in small quantities as a byproduct of the processing of cesium and lithium ores taken from a few small deposits in Canada, Namibia, and Zambia.
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6. Cesium - About Cesium: Cesium, also spelled as caesium, holds the title of the most electropositive stable element on the periodic table, with a single electron in its outermost shell. This metal is renowned for its high reactivity, spontaneously igniting upon exposure to air and violently exploding in water or ice at temperatures above -116 oC. Despite its mild toxicity, cesium’s high reactivity categorizes it as a hazardous substance. It is typically preserved in glass ampoules under vacuum or an inert gas like argon.
Cesium is the heaviest stable alkali metal and exhibits a silvery-gold hue. It is the softest element on the periodic table, with a Mohs hardness of 0.2. Cesium melts at 28 oC, making it one of the few elements that are liquid at or near room temperature.
Cesium has 39 known isotopes, tying it with xenon for the most known isotopes. Only one of these, 133Cs, is stable. Cesium was the first element discovered via spectroscopy by Robert Bunsen and Gustav Kirchhoff. The element’s name originates from the Latin word “caesius,” meaning “sky or heavenly blue,” which refers to the two brilliant blue lines in its emission spectrum.
Cesium is the 45th most abundant element on Earth. It is found in minerals such as pollucite, avogadrite, pezzottaite, londonite, rhodizite, beryl, and some potassium ores. The primary commercial source of metallic cesium is pollucite mining, while cesium radioisotopes are produced from nuclear reactor waste.
Cesium compounds are utilized in various organic chemistry functions, such as the hydrogenation of organic compounds and as a source of the fluorine anion in the case of cesium fluoride. Radioactive isotope cesium-137 is often employed in X-ray radiotherapy for cancer treatment.
In commercial and industrial applications, cesium salts serve as catalyst promoters, glass strengtheners, components of photoelectric cells, crystals in scintillation counters, and “getters” in vacuum tubes. Cesium formate brines are used in oil drilling to lubricate drill bits and maintain pressure. Thermionic energy converters use a vapor of cesium ions to determine the work function of the electrodes.
Cesium was used as a propellant in early ion propulsion engines for space exploration before xenon became the standard. The most accurate commercially available atomic clocks use the oscillation of the cesium-133 atom’s 9193 MHz hyperfine transition frequency, known as the “cesium standard.” This frequency is the primary time standard for defining the second and is critical to the data transmission infrastructures of cell phone networks, GPS, and the internet.
Cesium: Most cesium is obtained from the mineral pollucite (CsAlSi2O6). It is also obtained from the minerals lepidolite and zinnwaldite. It is mined in the USA, China, Russia and Brazil.
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7. Francium - About Francium: Francium is one of the rarest naturally occurring elements on the periodic table, surpassed only by astatine in its scarcity. Its high instability and radioactivity are characterized by its most stable isotope, Francium-233 (also known as actinium-K), which has a half-life of a mere 22 minutes. This extreme instability results in only approximately 20-30 grams of francium present in the Earth’s crust at any given moment, found in minuscule amounts in ores of uranium and thorium.
In a laboratory setting, francium can be generated by bombarding thorium with protons or radium with neutrons, but only in minuscule amounts. The most substantial quantity ever produced was a cluster of 30,000 atoms. Francium has never been seen in a bulk form due to its exceptionally low electronegativity, which causes it to vaporize instantly due to the intense heat of decay. As a result, scientists theorize that francium’s characteristics are likely akin to those of other alkali metals. Francium’s instability precludes it from having any commercial uses.
The existence of francium was foreseen by Dmitri Mendeleev in the 1870s. He dubbed it “eka-caesium” due to its similarities to cesium (“eka” signifies one element down on the periodic table). Francium was unearthed by French chemist Marguerite Catherine Perey at the Curie Institute in 1939 while she was examining the decay of actinium. Named in honor of her native country, francium was the final naturally occurring element to be discovered before scientists commenced synthesizing new elements in the laboratory.
Francium: Francium is virtually non-existent on Earth. It can be created by particle bombardment of radium or thorium.
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**8. Beryllium - About Beryllium: Beryllium, a lightweight and brittle metal, has been known to humans since the Ptolemaic dynasty of Egypt, primarily in the form of beryllium-containing minerals. These minerals were often recognized as gemstones. The element was first distinguished from other aluminum silicates in 1789 by chemist Louis Vauquelin, who is credited with its discovery. The name "beryllium" was suggested by Friderich Wohler, who isolated the pure metallic form of the element in 1828.
As the lightest of all metals except for lithium, beryllium is extremely hard and occupies the fourth spot on the periodic table. It leads the alkaline earth group of metals, which includes calcium and magnesium. Beryllium's high thermal conductivity, heat capacity, and melting point make it a useful industrial metal, particularly because its alloys are tough, stiff, and lightweight. Beryllium-copper, also known as beryllium bronze, is one such alloy that is harder, stronger, and more corrosion-resistant than other copper-based alloys, while conducting electricity and heat almost as well as pure copper.
Beryllium is primarily valued for its nuclear and electronic properties outside of its use as an alloying agent. It is largely transparent to X-rays due to its low atomic mass and density and remains stable under neutron bombardment. Beryllium is frequently used as a window or coating for x-ray tubes, and ultrathin beryllium foil is used in x-ray lithography. It also has various functions in the production of nuclear fuels and the construction of nuclear reactors.
Beryllium and its compounds are toxic when ingested, as the element can substitute for magnesium in essential enzymes, causing dysfunction. However, beryllium is poorly absorbed through the skin and the digestive tract, so beryllium poisoning by these routes is rare. The largest real safety concern with beryllium is the inhalation of dust containing the element, which can cause either acute lung ailments or a chronic lung disease called berylliosis.
Beryllium is not found in large quantities as a free element, but is a component of many naturally occurring minerals. These minerals occur only rarely in significant exploitable deposits, and both this and the expense of extracting the element from ore contribute to its high cost. The primary ores for the element are bertrandite, a beryllium sorosilicate hydroxide mineral, and beryl, an aluminum beryllium cyclosilicate. Some high-quality samples of beryl that contain impurities that produce attractive colors are considered precious stones; these include aquamarine, red beryl, and emerald.
Beryllium's high affinity for oxygen at high temperatures, along with its ability to reduce water, make it difficult to extract from its mineral forms. There are two processes currently in use to accomplish this: in the melt method, beryl is ground into a powder and heated to 3000 oF. It is then cooled and reheated with acid, producing beryllium sulfate, and treated with ammonia to produce beryllium hydroxide. In the sintering method, beryl is sintered at 1420F with sodium fluorosilicate and soda, producing sodium fluoroberyllate. This product is water soluble, and adding sodium hydroxide to a solution of fluroberyllate produces beryllium hydroxide. Beryllium hydroxide obtained by either method can be converted to either beryllium fluoride or beryllium chloride, which may be used directly or converted to pure beryllium metal.
Due to the complexity of this process, recycling beryllium alloys and scrap is substantially more energy efficient than producing new metal from ore. It is estimated that currently 20-25% of beryllium used annually is recycled, and the introduction of new recycling programs in recent years suggests that this number may rise in the near future.
Beryllium: Beryllium is obtained from the minerals beryl and bertrandite. Beryl provides green emerald and blue aquamarine gemstones. Other beryllium-bearing minerals include chrysoberyl, gadolinite and herderite. It is mined in the USA, China, Russia and Brazil.
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9. Magnesium - About Magnesium: Magnesium, a silvery-white alkaline earth element, is recognized as the lightest structural metal for industrial use. It was first isolated by Sir Humphy Davy in 1808 through the electrolysis of its oxide. The metals preceding it on the periodic table, despite being less dense, are not suitable for all-purpose applications due to the toxicity of beryllium and the dangerous reactivity of lithium.
With a density of 1.7 g/g/cm3, magnesium's density is two-thirds that of aluminum and one-fifth that of iron. Its density, combined with its excellent vibrational-damping properties and high specific heat (the fourth highest of all metals), makes it a crucial alloying agent that can reduce weight without significantly compromising strength or rigidity. Lightweight magnesium alloys are vital for structural components in various industries, including aerospace and defense, automotive, sports equipment, and consumer goods. Adding magnesium, a highly malleable metal, to aluminum significantly enhances its machinability.
Magnesium's chemical properties are also beneficial for numerous non-structural metallurgical applications. It serves as an additive during the production of nodular graphite cast iron, a reducing agent in the production of other metals such as uranium, titanium, or hafnium, and a desulfurizing agent in the production of steel. Researchers continuously study the properties and potential applications for magnesium metal. Recent developments include the production of extremely lightweight lithium-magnesium alloys for aerospace applications and the discovery that adding arsenic to magnesium significantly reduces the metal's susceptibility to corrosion.
Magnesium compounds are also important in modern industry. Magnesium reagents play essential roles in synthetic chemistry. A variety of magnesium compounds are used as fertilizer additives or water treatment agents, and magnesium chloride is frequently used for dust and ice control in construction industries. In the production of electronics products, magnesium is an important dopant of semiconducting crystalline materials.
A variety of magnesium compounds increasingly play a role in environmental preservation efforts. Natural minerals composed of magnesium silicates and ammonium salt can be used to capture carbon from the atmosphere, making them a candidate for inexpensive carbon sequestration. Magnesium-based metal-organic-frameworks (MOFs) are under investigation for use as molecular sieves to remove toxins from contaminated water, and pure magnesium is of interest for hydrogen storage applications.
Despite its ubiquity to the average consumer, magnesium metal is highly flammable, particularly in powdered form, and requires special health and safety guidelines. Fine particles or strips of magnesium ignite violently when exposed to air, burning in atmospheres of both oxygen and carbon dioxide and cannot be extinguished with water. The bright white flame radiates in the ultraviolet range, requiring special UV-blocking eye goggles to prevent damage to the retinas. Beyond these risks, however, magnesium is not only non-toxic, but the magnesium ion (Mg2+) is essential to the proper functioning of all living cell systems and is the fourth most common cation present in the human body.
Magnesium is the eighth most abundant element in the earth's crust and the second most abundant metal dissolved in seawater. Though it does not occur naturally by itself, it can also be found in minerals such as brucite, carnallite, dolomite, magnesite, olivine, talc, dolomite, and magnesite. Magnesium can be obtained either from seawater-derived brines using electrolysis, or extracted from minerals using a silicothermic reaction. The latter method of production is of considerable importance in modern industry, and is especially prevalent in China.
Magnesium: Magnesium is the eighth most abundant element in the Earth's crust. It is produced in large, aging stars from the sequential addition of three helium nuclei to a carbon nucleus. Magnesium is also obtained in smaller amounts from the magnesium-bearing minerals dolomite, magnesite, kieserite and brucite.
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10. Calcium - About Calcium: Calcium, a shiny, silvery-white alkaline earth element, is the fifth most abundant element in the Earth's crust. It is found in many common minerals, with calcium carbonate being one of the most prevalent, serving as the primary component of limestone. Humans have used limestone as a building material for millennia and also to produce lime, which has found uses in agriculture, tanning, and glassmaking, among other areas.
Calcium mineral products continue to be widely used in building materials. While limestone is no longer favored as a structural material due to its susceptibility to acid rain, crushed limestone is often used as a base material in road construction. Marble, a type of rock resulting from the metamorphosis of limestone, and gypsum, composed of calcium sulfate, are other widely known and used calcium minerals.
Calcium and its compounds play a crucial role as chemical agents. Calcium oxide, or quicklime, is used as a flux to remove impurities during steel refining, accounting for almost a third of lime consumption. Calcium hydroxide, often termed "builder's lime," is a major component of many mortars, plaster, and stucco, while quicklime is essential for making cement.
Calcium plays many essential roles in biological systems, making its compounds important in agricultural and medical applications. Agricultural lime, consisting of pulverized limestone, is added to soil as a source of calcium and magnesium for plants and to neutralize acidic soils. Calcium carbonate is used as an antacid, a calcium supplement, and as a phosphate binder in the treatment of patients with renal failure.
There are many other calcium compounds that play important roles in industry. Calcium hypochlorite is a common bleaching agent, calcium phosphate is used in the production of fertilizer, and calcium carbide was once used in carbide lamps but today is mostly important for the production of acetylene and in steelmaking.
Heating calcium-rich limestones decomposes the carbonate, producing quicklime. The addition of water to quicklime produces calcium hydroxide, often termed slaked or hydrated lime. Most industrial calcium products use one of these as raw material, with the exception of those products that require the use of gypsum. Calcium metal has comparatively few uses, but when needed is produced by mixing calcium oxide with fine particles of aluminum, and then heating the mixture in a vacuum.
Calcium: Calcium is the fifth most abundant element in the Earth's crust and makes up more than 3% of the crust. Calcium does not occur as a free element in nature, but as compounds in rocks. These calcium compounds are commonly found in rocks such as limestone, dolomite, and marble.
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11. Strontium - About Strontium: Strontium, a unique element, was first identified in 1790 by Adair Crawford, a Scottish physician. He discovered it while examining a mineral sample from Strontian, Argyleshire, which he initially thought was barium carbonate. However, the sample's unusual chemical properties led him to propose that it contained a new element. This hypothesis was confirmed by his peers, and the element was named "strontium" after its place of discovery. The pure metal form of strontium was first isolated in 1808 by Sir Humphry Davy, who overcame the element's high reactivity with water and air by using electrolysis on a mixture of mercury and strontium oxides.
Strontium found its first industrial application in sugar extraction from sugar beet molasses through a process known as the Strontian process. Although this method is now outdated, strontium continues to be used due to the unique properties of its compounds. For instance, strontium salts burn a bright red, making them ideal for use in fireworks, flares, and tracer ammunition. Strontium oxide, another compound, is used in pottery glazes as a safer alternative to toxic lead or barium compounds. It also enhances the quality of glass by increasing its hardness, strength, and refractive index, making it suitable for optical applications. Strontium oxide-enriched glass also blocks UV and X-ray radiation, making it a key component in cathode ray tube (CRT) display faceplates.
In the medical field, strontium has several applications due to its chemical similarity to calcium. It is absorbed by the bones and promotes calcium uptake, thereby increasing bone density. Strontium ranelate is used to treat osteoporosis, while the radioisotope strontium-89 is used to alleviate pain from metastatic bone cancer. Strontium chloride is used in toothpaste to treat tooth sensitivity.
Strontium metal, though not commonly used, is added to certain aluminum alloys to enhance their castability. It is also occasionally used as a chemical reagent.
Strontium is highly reactive, like other alkali earth metals, and is not found naturally in its pure metal form. Its primary mineral deposits are celestite (a strontium sulfate mineral) and strontiantite (a carbonate mineral). While most strontium compounds are derived from the carbonate, celestite is more commonly mined due to its prevalence in economically exploitable deposits. Therefore, most extracted strontium is converted from the sulfate to the carbonate. When strontium metal is required, it is produced by reducing strontium oxide with aluminum.
Strontium: Obtained from the minerals strontianite (strontium carbonate) and celestite (strontium sulfate). It is mined in Mexico, Turkey, Iran, Spain, and Algeria.
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12. Barium - About Barium: Barium, the heaviest and most reactive stable element in the alkaline earth family, shares similarities with its alkali metal counterpart, cesium. Its discovery traces back to the early 17th century in Bologna, Italy, where alchemists were intrigued by rocks composed of barium sulfate that emitted a phosphorescent red glow for years after being burnt and exposed to sunlight. The element's name, "barium," originates from the alchemical term for barium sulfate, "baryta," which is based on the Greek word "barys," meaning "heavy" or "dense." Sir Humphrey Davey isolated the element in 1808 through electrolysis of molten barium salts, a technique he also used to isolate other alkali metals.
Barium is not found in its free form in nature due to its high reactivity. It primarily exists as barium sulfate in the mineral berite (also known as barytes or heavy spar), which is its main commercial source. The element is also found in witherite (barium carbonate) and the fluorescent blue gemstone benitoite (barium titanium silicate), the official state gemstone of California. Natural barium is a mix of seven different isotopes and can be produced either by electrolysis of barium chloride or by reducing barium oxide with elemental aluminum.
Barium, chemically similar to calcium, is a shiny silver metal that turns gray when its surface oxidizes in contact with air. The element is extremely electropositive and highly reactive, leading to explosive exothermic reactions when it comes into contact with water and alcohols or when it reacts with nonmetals such as carbon and nitrogen upon heating. Due to its flammability, barium is stored under mineral oil for safety. Soluble barium compounds are considered extremely poisonous due to the toxicity of the Ba2+ ion and must be handled with care.
Barium has various forms with commercially useful properties. As a metal or when alloyed with aluminum, it serves as a "flashed getter" in vacuum tubes to combine with and remove residual oxygen or moisture. It can also enhance the structure of aluminum-silicon alloys and increase the creep resistance of lead-tin alloys. Barium can alloy with other metals such as zinc, lead, nickel, and tin to form intermetallic phases and alloys used as bearing alloys, deoxidizers, and the basis for spark plug wires in the form of barium-nickel alloys. Barium compounds such as carbonates, chlorides, oxides, hydroxides, and peroxides have various applications, including as bleaching agents, desiccants, water softeners, components of glass and ceramics, additives to oil drilling fluids, green colorings for fireworks, and rat poisons. Barium sulfate, uniquely insoluble in water and thus nontoxic, is used as a radiopaque contrast media for X-ray and CAT scan imaging of the gastrointestinal tract in high purity form. It is also used as a white pigment in paints, ink, and coatings, either by itself or in combination with zinc sulfide (a material known as lithopone), and as a filler for rubbers and plastics.
Certain crystalline ceramic forms of barium possess unusual properties that give them specialized high technology applications. Yttrium barium copper oxide (YBCO) is a well-known high-temperature superconductor, the first material ever discovered to exhibit superconductivity above the temperature of liquid nitrogen (77 K). Magnetic strips of credit cards and data storage devices utilize barium ferrite, a magnetic material that can take on a complex ferromagnetic fluid phase at room temperature. Barium titanate and barium zirconate (when combined, known as barium zirconate titanate or BZT) are piezoelectric, ferroelectric perovskite crystals that can function as dielectric materials in capacitors, electrolytes in solid oxide fuel cells, and nonlinear optical crystals. Barium fluoride is another common optical material used in lenses, windows, and scintillators due to its wide transparency in the ultraviolet and infrared spectra.
Barium: Obtained from the minerals barite (barium sulfate) and witherite (barium carbonate). It is mined in China, India, and the USA.
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13. Radium - About Radium: Radium, a highly radioactive element, was discovered by Marie and Pierre Curie during their work on uranium ore, also known as pitchblende. This discovery, which came shortly after they discovered polonium in 1898, was notable due to radium's faint-blue luminescence under ambient conditions, a characteristic not shared by other radioactive elements. Radium is 2.7 million times more radioactive than an equivalent amount of uranium and is so rare that several tons of uranium ore are needed to produce just one gram of radium. Radium is typically available in compound forms, primarily radium chloride or radium bromide, due to its high radioactivity and relative scarcity. Marie Curie successfully isolated radium in 1911 by performing electrolysis on radium chloride. Radium was also the first element to be synthetically produced in the United States, achieved by Dr. John Jacob Livingood in 1936 at the University of California, Berkeley's radiation laboratory through deuteron bombardment of bismuth.
Radium's luminescent properties led to its widespread industrial and commercial use in the early 20th century, including in watch faces, aircraft instrumentation, and nuclear panels. However, after many workers fell ill, radium paint was banned in the early 1960s, with cobalt, promethium, and tritium taking its place in industry. Radium's fascinating properties led to its infusion in many everyday products, such as toothpaste and spa water, for its supposed curative powers. It was only banned when a link was established between radium and the illnesses of otherwise healthy individuals. Radium was also used in several medical treatments in the 1920s and 1930s that have since fallen out of favor. Today, only about five pounds of radium are produced annually, with most of it being used for medical research.
The Curie, a standard unit of measure of radioactivity, is based on radium's decay. This value is equal to the number of atoms in a one-gram sample of 226Ra that will decay in one second, which is about 37 billion decays per second. Radium decays into radon, which is also radioactive, and eventually into lead. Four isotopes of radium occur naturally, with an additional 21 isotopes that can be synthetically generated. 226Ra is the most abundant isotope, with a half-life of approximately 1600 years, and is a naturally occurring product of 238U decay. Other natural isotopes of radium are produced through uranium or thorium decay, and all natural occurrences of radium are found on Earth only in uranium ores.
Radium: Found in very minute amounts in uranium-bearing rock. It is also produced in very small amounts in nuclear reactors.
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14. Scandium - About Scandium: Scandium, represented as element 21 or "ekaboron" on Dmitri Mendeleev's 1869 periodic table, was not discovered until ten years later. Lars Fredrik Nilson, who found it in the minerals euxenite and gadolinite, named it scandium, paying homage to his homeland, Scandinavia. Nilson managed to prepare high purity scandium oxide, but it wasn't until 1960 that pure scandium metal was produced in substantial quantities. The relatively brief history of scandium production has restricted its industrial uses, keeping production low and prices high. However, scandium is not rare in absolute terms, and increased recognition of its benefits could potentially drive up demand and production.
Scandium is frequently used in small amounts to stabilize or enhance the properties of a host material, a technique known as doping. It is most commonly found in scandium-aluminum alloys, which are valued for their lightness and strength. However, these alloys are less commonly used than the less expensive titanium-aluminum alloys. Scandium-aluminum alloys are used in some aircraft components and sports equipment, including baseball bats, bicycle frames, and lacrosse sticks. Garnets containing scandium are used as gain media in lasers, including those used in dental surgery. Scandium-stabilized zirconia is recognized as a high-efficiency electrolyte in solid oxide fuel cells. Lastly, scandium oxide is used in metal-halide lamps to produce high-intensity white light that resembles sunlight.
Scandium: Obtained from the minerals thortveitite, euxenite, and gadolinite. It is mined in the USA, China, Russia, Australia, and India.
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15. Yttrium - About Yttrium: Yttrium, an element that was initially suspected to be tungsten, was discovered by Carl Axel Arrhenius in 1787 in a rock he found in a quarry near the Swedish village of Ytterby. Although other chemists disproved his initial suspicion, four new elements were eventually identified from Arrhenius's ytterbite. The first of these was recognized as a new oxide by Johan Gadolin in 1787 and named yttria, leading to the new element within this oxide being called yttrium. Today, yttrium is one of four elements named after the village of Ytterby, the others being terbium, erbium, and ytterbium.
Yttrium, a fairly common rare earth element, serves a wide range of functions. One of the most widely used yttrium-based materials is yttria-stabilized zirconia (YSZ), an extremely hard, non-reactive ceramic that remains chemically stable even at high temperatures. YSZ can be purchased in the form of water-based ceramic pastes for use by hobbyists, formed into knife blades that are harder than steel, used in restorative dentistry to construct crowns and bridges, and coated on metal components in engines to prolong their life by serving as a thermal barrier. Additionally, YSZ can conduct ions, a property that along with its stability at high temperatures lends it to use as a solid electrolyte in solid oxide fuel cells as well as in sensors such as those that detect oxygen content of exhaust fumes.
In addition to being integral to inherently useful materials like YSZ, yttrium can serve as a major component of substrate crystals and ceramics that can be doped or otherwise manipulated to exhibit useful properties, and can also serve as a dopant itself in some cases. Doping yttrium oxide, yttrium orthovanadate, or yttrium aluminum garnet (YAG) with certain lanthanide ions yields phosphors that are used in television and computer display screens in as well as in lighting applications. Notably, europium-doped yttrium lattices produce red phosphorescence that is essential for modern color screens, and cerium-doped YAG is used in the production of white LEDs. Yttrium iron garnets exhibit a range of properties, including the Faraday effect, low absorption of infrared wavelengths, and a high Q factor for microwave frequencies, that make them useful for microwave communications devices and magneto-optical systems. Yttrium oxide, yttrium orthovanadate, yttrium lithium fluoride, yttrium iron garnet and yttrium aluminum garnet can all be used in combination with appropriate dopants as gain media for lasers. YAG crystals have also been used as gemstone simulants, but have served this function less since the introduction of synthetic cubic zirconia.
As a dopant, yttrium is used to impart shock resistance and low thermal expansion to glasses and ceramics, including the glass used in many camera lenses. In metal alloys, it generally improves workability and resistance to crystallization and to oxidation at high temperatures. It is specifically used to reduce grain size in alloys of chromium, molybdenum, titanium, and zirconium, increase strength of aluminum and magnesium, and to produce nodular cast iron, which has increased ductility as compared to conventional cast iron.
Aside from these major industrial functions, yttrium has a few other applications. Several yttrium compounds are notable for their ability to function as superconductors up to relatively high temperatures. In particular, yttrium barium copper oxide was the first material known to exhibit superconductivity at a temperature above the boiling point of nitrogen. In medicine, radioactive isotope yttrium-90 is used in cancer treatment and for some types of high-precision surgeries. Yttrium catalysts are used in the polymerization of ethylene. Yttrium is sometimes also found in the electrodes of spark plugs and mantles for propane lanterns.
Yttrium is found in most rare earth minerals and some uranium ores. Despite having a lower atomic weight than even the light rare earths (LREE), it behaves more like a heavy rare earth element (HREE), and occurs in the highest concentrations in minerals rich in HREEs, most notably xenotime. It can be found in smaller quantities in LREE-rich minerals like monazite and bastnasite, and can make up a significant percentage of rare earth concentrates derived from ion adsorption clays. Pure yttrium oxide is usually isolated from mixed rare earth oxide ores by dissolving them in sulfuric acid and fractionating the mixture by ion exchange chromatography.
Yttrium: Present in nearly all rare-earth minerals. It is obtained by mining the minerals bastnasite, fergusonite, monazite, samarskite, and xenotime, which are mined in the USA, China, Australia, India, and Brazil.
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16. Lanthanum - About Lanthanum: Lanthanum, a rare-earth element, was discovered by Swedish chemist Carl Gustav Mosander in 1839 during his work on an impure sample of cerium nitrate.
Lanthanum, like most rare-earth elements, is used sparingly to modify the key properties of other materials. Lanthanum oxide, for instance, is added to glass to increase its resistance to alkalis, strength, refractive index, and low dispersion, and can be used to manufacture infrared-absorbing glass. Lanthanum is also a crucial component of ZBLAN glass, which has superior infrared light transmittance and is used in fiber-optic communication systems. These glasses are used in specialized optical applications such as telescope lenses. Lanthanum-doped ceramic materials are used as both anodes and cathodes in solid oxide fuel cells. Adding small amounts of lanthanum to steel enhances its malleability, ductility, and impact resistance, while adding lanthanum to molybdenum reduces its hardness and temperature sensitivity.
Many rare earth compounds can emit light when they absorb energy from an external source. The first commercial use of lanthanum took advantage of this property to produce gas lantern mantles. However, these mantles produced a green-tinged light and were not very successful. Their creator, Carl Auer von Welsbach, later found more success with a cerium-containing mantle. Today, lanthanum phosphors like lanthanum fluoride are used in fluorescent lamps, and cerium-doped lanthanum bromide and chloride scintillators serve as radiation detectors by producing light when they absorb ionizing radiation.
Lanthanum has several other properties that are exploited in a variety of applications. Many lanthanum compounds can emit electrons when heated, a process known as thermionic emission. Lanthanum boride crystals are used as electron emission sources for electron microscopes and ion thrusters used in spacecraft. The thermionic emission of electrons from lanthanum compounds is also exploited in carbon arc lamps, where lanthanum compounds are sometimes components of one of the electrodes. Lanthanum also binds phosphates in solution. Some water treatment products use this property to remove the free phosphates that feed algae, while the drug lanthanum carbonate uses it to absorb excess phosphate in the blood of patients in end-stage kidney failure. Lanthanum catalysts are widely used in the industrial process of refining petroleum for fuel. Additionally, lanthanum catalysts are being investigated for use in many other processes, including photocatalytic hydrogen production and production of syngas from methane.
Lanthanum is often a component of hydrogen sponge alloys-metals that can absorb and store up to 400 times their own volume of hydrogen gas. These alloys are most commonly used as the negative electrode of nickel-metal hydride (NiMH) batteries. NiMH batteries are rechargeable batteries with high storage capacity and are important for the development of green technologies such as electric vehicles.
Many lanthanum-containing thin film compositions have been investigated in the search for high-k gate dielectrics for use in integrated circuits. Silicon dioxide gate dielectrics have been standard for decades, but the industry has reached the limit of thinness for silicon layers that can serve as an effective gate, and the development of alternate materials could theoretically allow for further miniaturization of microelectronics.
Lanthanum is a light rare earth most commonly obtained by processing the rare earth minerals monazite and bastnasite.
Lanthanum: Mainly obtained from lanthanum-rich monazite and bastnasite. Other lanthanum-bearing minerals include allanite and cerite. It is mined in the USA, China, Russia, Australia, and India.
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17. Actinium - About Actinium: Actinium, a silver-white metallic element, is the first member of the actinides group in the periodic table, a series of elements known for their radioactivity. Its relative scarcity on Earth and high radioactivity have historically limited its commercial or industrial applications. However, ongoing scientific research into both medicine and spacecraft power systems may change this.
French chemist Andre-Louis Debierne discovered actinium in 1899 while isolating residue left by Marie and Pierre Curie during their extraction of radium from uranium ore. Actinium is so scarce that only 0.2 mg of the element can be extracted from one ton of uranium ore. Due to this scarcity, actinium is usually obtained by irradiating a radium isotope (226Ra) with neutrons in a nuclear reactor. The resulting actinium then becomes a neutron source of its own, and can be used for targeted radiation therapy in cancer treatments. It is currently becoming a preferred element in medical research for this purpose due to its high radioactivity - roughly 150 times that of radium. This high radioactivity is also attractive to spacecraft designers, who may pursue actinium as the active element in future radioisotope thermoelectric generators.
Actinium rapidly oxidizes in the presence of oxygen and moisture, and it is in this state where the vast majority of its chemical compounds occur. The oxide of 227Ac pressed with beryllium, often referred to as AcBe, is also an efficient neutron source with the activity exceeding that of the standard americium-berylllium and radium-beryllium pairs. AcBe-based neutron probes are used to measure water presence and density in soil, in neutron radiography, and in other radiochemical testing applications. Though these compounds are readily achievable in the laboratory, they are typically used solely for research purposes with few commercial applications.
The only naturally occurring isotope of actinium is 227Ac. Thirty-six radioisotopes of actinium have been identified, all with half-lives ranging from 69 nS at the shortest (for 217Ac) to 21.77 years at the longest (227 Ac). Due to its convenient half-life attributes, the presence of 227Ac in oceanic waters is utilized as an estimate to model and calculate vertical mix rates. Over time, actinium decays into thorium and francium, with beta decay dominating over alpha decay by a factor of roughly 71:1.
Actinium: Part of the decay series of uranium. As such it is found in very minute amounts in uranium-bearing rock. It is also produced in very small amounts in nuclear reactors.
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18. Titanium - About Titanium: Titanium, a silver-white metallic element, was first discovered in 1791 by Reverend William Gregor, an English clergyman and mineralogist. He found a black magnetic sand, now known as ilmenite, and hypothesized that it contained a new element. However, his discovery didn't gain much attention until several years later when Martin Heinrich Klaproth confirmed the presence of a new element in a similar magnetic mineral and named it titanium, after the Titans of Greek mythology. The pure element was finally isolated from such minerals in 1887 by Lars Fredrik Nilson and Otto Pettersson after many failed attempts.
Most titanium ore is processed into titanium dioxide, a material used in a wide range of products. With its high index of refraction and optical dispersion, the bright white powder serves as an excellent white pigment and opacifier, widely used in the production of paints, paper, plastics, and ceramic glazes. It's also added as a strengthening filler in cements and graphite composites and used in sunscreen due to its ability to absorb UV light. The material is also of interest for its photocatalytic abilities; in the presence of sunlight, it produces hydroxyl radicals, which are exploited in applications such as dye-sensitized solar cells, self-cleaning glass coatings, hydrolysis catalysis, and paints and cements that can reduce air pollution.
Titanium metal, valued for its high strength-to-density ratio and high resistance to corrosion and fatigue, is used in a wide range of alloys. These alloys are widely used in aircraft, armor plating, naval ships, spacecraft, and missiles. Additionally, titanium is used in jewelry for its high durability and ability to be anodized to produce a wide variety of colors. The metal is also biocompatible and is frequently used in medical implants and surgical tools, either alone or as part of metal-ceramic composites. Titanium is especially useful in dental and orthopedic implants, as it can integrate with bone.
Another major commercial use of titanium is in ceramics. Titanium ceramics are typically extremely hard and often exhibit useful electrical properties. They may be used in composite structural materials such as cermets or in extremely hard cutting tools for metal machining, or in technical applications such as electronics or medical implants. Barium titanate and lead zirconate titanate are important electroceramics found in ceramic capacitors, transductors, and sensors. Lithium titanate is an important conductive ceramic used in some lithium-ion batteries and in molten carbonate fuel cells. Titanium nitride is notable for being both conductive and biocompatible, which allows its use in implants including bioelectronics, and as a barrier metal in the manufacture of microelectronics. Other notable titanium compounds include titanium disulfide, an inorganic material of interest for use in improved battery designs and nanostructured hydrogen storage solutions.
Titanium occurs primarily as the minerals rutile and ilmenite, which are often found as components of heavy mineral sands. These minerals cannot be processed to titanium metal through high-temperature reduction with carbon, as is the case for some other metals. Instead, the pure metal is produced by first chlorinating titanium minerals, purifying the resultant titanium chloride via distillation, and then reducing the purified chemical using magnesium or sodium in an inert atmosphere. This complex process largely accounts for the high cost of titanium metal, but alternative, potentially cheaper processes are under development. Some titanium alloys can be made via direct reduction of titanium ores, and this allows their production without the expense of producing pure titanium. Additionally, most commercial titanium compounds are acquired from mineral concentrates without passing through a metallic phase. The most commonly used titanium compound, titanium dioxide, is produced using either the sulfate process or the chloride process, depending on the source material and the purity required in the final product.
Titanium: Chiefly obtained from the minerals rutile, ilmenite and rarely from anatase (beta-titanium dioxide). Other titanium-bearing minerals include perovskite, sphene, and titanite. These minerals resist weathering and are concentrated in placer deposits and wind-blown sand deposits.
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19. Zirconium - About Zirconium: Zirconium, a silver-white metallic element, was first discovered in 1791 by the English clergyman and mineralogist Reverend William Gregor. However, it was Martin Heinrich Klaproth who recognized that the mineral zircon contained a new "earth" distinct from the already well-characterized alumina. He named the new metallic element after its source mineral in 1789. The pure form of the metal was first isolated by the renowned chemist Jons Jakob Berzelius in 1824.
The majority of commercially used zirconium is found as zirconium dioxide, also known as zirconia. Zirconia can exhibit three different crystal structures depending on temperature. Unstabilized zirconia may crack when heated or cooled due to transitions between these phases. However, stabilized cubic zirconia, produced via the addition of other metal oxides, is generally extremely stable across wide temperature ranges. Stabilized zirconia is frequently used as a refractory ceramic material in lab crucibles, metal furnaces, thermal barrier coatings, and as a surface coating for foundry molds. It is also biocompatible and is frequently used as a material for medical implants, either alone, as a coating for metal implants, or in composite metal-ceramic devices.
Zirconium is also a component of several other important ceramic materials. Zirconium carbide and zirconium nitride are extremely hard ceramics generally used as refractory materials or cutting tools. Additionally, zirconium is a component of some electroceramics, the most well-known example being lead zirconate titanate, a material frequently used in ceramic capacitors, sensors, and actuators.
A few other zirconium compounds have niche applications as chemical agents. Ammonium zirconium carbonate and potassium zirconium carbonate are used in paper coatings for the production of high-quality prints. Other zirconium compounds find use as crosslinkers in polymers or in inks to promote adhesion to metals and plastics.
In its metallic form, zirconium is used as an alloying agent. Its primary advantage is its high resistance to corrosion, which makes it useful in specialty alloys designed for use in highly corrosive environments. Additionally, zirconium is biocompatible, making it useful in alloys for biomedical implants, and has a low absorption cross-section for thermal neutrons, which dictates its use in nuclear fuel cladding.
Zircon, the source of all commercially used zirconium, is a silicate mineral found as a minor component of heavy mineral sands, which also contain the source minerals for titanium. The two elements are therefore co-products of the same mining operations. Most zircon is never converted to the pure element, and is instead converted to zirconium dioxide, which is the starting material for most other zirconium products. Zirconium metal is produced via the Kroll process, which requires converting zircon to zirconium tetrachloride, which is then reduced to the metal using magnesium. Zircon is also used directly as an opacifier in decorative ceramics, and large crystals of sufficient quality are cut for use as gemstones.
Zirconium: Chiefly obtained from zirconium dioxide (baddeleyite) and zircon. These relatively heavy minerals are found in placer deposits and wind-worked sands, and are mined in Australia, South Africa, the USA, Russia, and Brazil.
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20. Hafnium - About Hafnium: Hafnium, a lustrous, silver-gray metal, was first predicted to exist by Dmitri Mendeleev's periodic table in 1869 as an element with 72 protons that would be chemically similar to zirconium. This prediction was later supported by the theoretical models of elements by Henry Moseley and Niels Bohr. However, it wasn't until 1923 that Georg von Hevesy and Dirk Coster provided the first empirical evidence of this elusive element, making it the penultimate element with stable isotopes to be discovered (followed by rhenium two years later). Working at the Bohr Institute of Theoretical Physics in Copenhagen, the two chemists identified the new element via x-ray spectroscopy analysis of a zirconium ore and named it "hafnium" after Hafnia, the Latin name for Copenhagen.
Hafnium is extremely similar to zirconium, with nearly identical atomic radii, and the two always occur together in nature in a continuous solid-solution, making them two of the most difficult elements to separate. Primarily zirconium-based minerals typically contain 1-3% hafnium, the most common being zircon (zirconium silicate) with up to 4% hafnium by content. Hafnium metal is primarily obtained as a byproduct of producing high-purity nuclear grade zirconium metal. The metals are typically chemically separated via a liquid-liquid extraction process that utilizes the slightly different solubilities of the two metals' salts.
In its elemental form, hafnium is a ductile gray metal with a brilliantly lustrous silver sheen. Exposure to air causes the metal to form an impenetrable oxide film on its surface which lends the metal an extremely high resistance to corrosion and attack by most acids and alkalis. Hafnium's melting point is high among its fellow transition metals, leading to its occasional classification as a refractory metal. Like many other metals, hafnium as a fine powder is pyrophoric, meaning that it can ignite in air; for this reason, it is considered a hazardous material despite being non-toxic to humans. Though hafnium shares many chemical and physical properties with zirconium, the two metals differ significantly in their densities (hafnium being roughly twice as dense) and their nuclear properties. Hafnium is an excellent neutron absorber with a high thermal neutron cross section, about 600 times that of zirconium, and one of its primary commercial uses is in control rods of nuclear reactors. It has also been used to enhance radiotherapy in the treatment of cancer.
Compound and alloy forms of hafnium are notable for their refractory properties. The melting points of several hafnium compounds are unparalleled within their respective groups: hafnium nitride's (3310 oC) is the highest of any nitride, hafnium carbide's (3890 oC) is the highest of any known binary compound, and tantalum hafnium carbide's (4215 oC) is the single highest of any known compound. Thus, forms of hafnium are frequently employed in high-temperature environments as components of furnace linings, ceramics, rocket thrusters and jet engines for the aerospace industry, nozzle tips for plasma arc cutting, and wear-resistant coatings. High-performance superalloys typically contain hafnium in combination with metals like titanium, tungsten, and niobium; the metal improves creep ductility, strengthens grain boundaries, and increases corrosion resistance. Other applications for hafnium include serving as an oxygen and nitrogen "getter" in vacuum tubes and incandescent lighting, in geological dating (as isotopes), and in organic catalysis. Additionally, compounds like hafnium oxide and hafnium silicate have shown great promise as high-k dielectric materials that increase the efficiency of semiconductor devices such as integrated circuits and transistors in the field of advanced microelectronics.
Hafnium: Part of the decay series of uranium. As such it is found in very minute amounts in uranium-bearing rock. It is also produced in very small amounts in nuclear reactors.
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21. Rutherfordium - About Rutherfordium: Rutherfordium, a radioactive element bearing the atomic number 106, has a history steeped in international rivalry and scientific discovery. Its genesis traces back to the 1960s when laboratories in California and the Soviet Union independently synthesized the element, leading to a contentious debate over its discovery rights.
The International Union of Pure and Applied Chemistry (IUPAC) intervened amidst the dispute, temporarily designating the element as Unnilquadium (Unq). The American and Soviet teams proposed the names Rutherfordium and Kurchatovium respectively, honoring two titans of nuclear physics - Ernest Rutherford and Igor Kurchatov. The controversy was finally put to rest in 1997 when IUPAC officially christened element 106 as Rutherfordium, while element 105 was named Dubnium, acknowledging the contributions of the Soviet Joint Institute of Nuclear Research.
Rutherfordium's fleeting existence, characterized by an extremely short half-life, has resulted in only minuscule quantities of the element being produced. Its chemical properties remain largely uncharted. However, its position as the inaugural transactinide element on the periodic table suggests that it shares fundamental characteristics with other period 4 elements like zirconium and hafnium. Predictions indicate that Rutherfordium exists as a solid at room temperature, possessing a hexagonal close-packed crystal structure and a density approximating 23 g/cm3.
Rutherfordium: Rutherfordium is a synthetic element and is not found naturally. It is obtained by particle bombardment of californium or curium.
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22. Vanadium - About Vanadium: Vanadium, a d-block transition metal, is known for its vibrant colors in various oxidation states: purple/lavender/violet (+2), green (+3), blue (+4), and yellow (+5). This color spectrum inspired Swedish chemist Nils Gabriel Selfstrom to name the element after Vanadis, an alias for Freyja, the Norse goddess of beauty, love, and fertility. However, the element's first discovery traces back to 29 years earlier in Mexico by Spanish mineralogist Andres Manuel del Rio. He isolated several compounds from a mineral he termed "brown lead" (later renamed vanadinite) and identified a new element he initially named panchromium, meaning multi-colored, and later renamed to erythronium, Greek for "red," due to the red color the compounds exhibited when heated.
Vanadium is the fifth most abundant transition metal in the earth's crust, composed of two isotopes, one stable (51V) and one radioactive (50V). It is found in over 65 different minerals, including ores of titanium, uranium, and iron, phosphate rocks, and fossil fuel deposits such as crude and shale oils. The most common form of the element obtained is vanadium pentoxide, while the metal itself is more challenging to produce due to its high reactivity at the melting point of its oxide.
Vanadium's thermal and electrical conductivity and strength surpass that of titanium, making it a popular choice in the production of alloys. Even a small amount of vanadium can significantly increase the tensile strength and hardness of steel, providing shock and vibration resistance. This vanadium steel, also known as "tool steel" or "high-speed steel," is one of the strongest alloys used in various equipment parts, including armor plates, piston rods, and jet engines.
The most commercially significant form of vanadium is vanadium pentoxide, primarily used in the production of ferrovanadium and as an industrial catalyst for the production of sulfuric acid. Some vanadium compounds have applications in the field of medicine, such as treatments for diabetes mellitus and nutritional supplements. However, all vanadium compounds are considered toxic to humans to some degree, particularly those with vanadium in a higher valence state.
Vanadium's role in advanced and emerging technologies is increasing due to the unique properties of its compounds. In particular, vanadium redox (or flow) batteries have gained attention in recent years as viable alternatives to the dominant lithium-ion technology currently in use. These rechargeable batteries store energy via continuously recyclable aqueous solutions of vanadium redox couples in both electrodes, eliminating the risk of cross-contamination of the electrolyte and yielding a low cost, high-efficiency energy source that has been investigated for potential use in hybrid and electric vehicles. Two-dimensional nanosheets of vanadium pentoxide have demonstrated favorable properties that could lead to their use as electrodes in supercapacitors. Vanadium dioxide has also gained attention for its unique properties. It is one of the few known materials that undergoes a metal-insulator transition: acting as an insulator at low temperatures, the material rearranges its electrons in an abrupt shift (taking only 10-trillionth of a second) to act like a conductor at 67 degrees Celsius. At 65 degrees, it enters a solid-state triple point-the first material in which researchers have ever accurately pinpointed. Some experiments into the uses of vanadium dioxide include the work of researchers at the Lawrence Berkeley National Laboratory, who used vanadium dioxide to fabricate a micro-sized artificial muscle-motor that exhibited extremely high power density and resilience. Thin ribbons of vanadium dioxide alternating with graphene have shown to be a highly efficient cathode material for lithium-ion batteries that could significantly increase power and energy density, and it has also been investigated as a metamaterial.
Vanadium: Vanadium is found in several minerals, including vanadinite, carnotite, and patronite.
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23. Niobium - About Niobium: Niobium, a d-block transition metal, is part of the refractory metals group, known for their high melting point and resistance to oxidation. Its discovery traces back to 1801 by British chemist and mineralogist Charles Hatchett, who named it "columbium." However, it was not until 1866 that niobium and tantalum were definitively proven to be distinct elements, despite their chemical similarity and co-occurrence in nature.
Niobium is found alongside tantalum in minerals such as columbite, tantalite, euxenite, manganocolumbite, manganotantalite, aeschynite, samarskite, simpsonite, tapiolite, and pyrochlore. The main commercial source of niobium is pyrochlore, from which it is extracted as ferroniobium. It can also be prepared as a byproduct of tin extraction.
As a soft and shiny gray transition metal, niobium is ductile and malleable and can be cold worked over 90% before requiring annealing. It has the lowest density, melting point, modulus of elasticity, and thermal conductivity among refractory metals, and the highest thermal expansion. A thin film of niobium oxide provides surface passivation, making the metal resistant to corrosion and attack by acids.
Niobium's resistance to oxidation, coupled with its high strength and melting point, makes it a crucial component of alloys and superalloys such as Inconel 718, C103, and ferroniobium. These are used in high-temperature, high-stress applications like combustion equipment, jet engines, rocket assemblies, gas pipeline production, and airframe systems of spacecraft. Niobium is also used in nuclear reactors due to its low neutron absorption cross-section.
Niobium has the largest magnetic penetration depth of any element and is one of the three elemental type-II superconductors. Niobium-tin alloy (Nb3Sn) was the first such material discovered in 1961 at Bell Labs. Niobium-tin wires, niobium-zirconium wires, and niobium-titanium wires are used in the high power superconducting magnets in MRI scanners, nuclear magnetic resonance instruments, and CERN. Niobium oxide has been used in metallic glass and smart windows, and is increasingly used in electronics and optics due to its high dielectric constant. Lithium niobium oxide (lithium niobate, or LiNBO) is a common non-linear optical crystal. Due to its similar properties and wider availability, niobium is a potential lower-cost substitute for tantalum used in capacitors and transistors in microelectronics.
Niobium: Niobium primarily occurs in oxide minerals of the pyrochlore group, which are most commonly found in carbonatites and alkaline granite-syenite complexes.
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24. Tantalum - About Tantalum: Tantalum, a lustrous blue-gray transition metal, shares a close chemical relationship with niobium. These two elements are never found as free elements on Earth and are always intertwined in minerals such as tantalite, columbite, samarskite, microlite, wodginite, euxenite, fergusonite, and polycrase. The minerals tantalite and columbite, also known as niobate, share the same chemical structure, with their names reflecting the relative proportions of tantalum to niobium.
The intertwined history of these two elements began in 1801 when British chemist and mineralogist Charles Hatchett analyzed a mineral sample sent from the American colonies by Connecticut governor John Winthrop. Hatchett discovered a new element in the sample, which he named "columbium" after Columbia, the symbolic female embodiment of the United States. The mineral itself came to be known as columbite.
In the same year, in Uppsala, Sweden, chemist Anders Gustaf Ekeberg extracted an oxide from tantalite that was highly resistant to acid attack. He named this new element "tantalum" after the Greek mythological figure Tantalus. However, later that year, British chemist William Hyde Wollaston declared that columbium and tantalum were the same element, despite the difference in density between the two oxide forms, and that tantalum should be its official name.
The scientific community faced much confusion in the following years. In 1845, German chemist Heinrich Rose suggested that tantalite contained two additional elements besides tantalum, which he named "pelopium" and "niobium" after Pelops and Niobe, the mythological daughters of Tantalus. In 1847, R. Hermann announced the discovery of a new element, "ilmenium," from the mineral samarskite. However, it was later shown that pelopium and ilmenium were mixtures of tantalum and niobium. The distinction between tantalum and niobium was not empirically proven until the 1860s by Jean Charles Galissard de Marignac, and pure tantalum was not isolated until 1903 by Werner von Bolton.
Tantalum is a member of the heat-resistant refractory metal group. It is hard and dense, yet also ductile and highly malleable. Its resistance to corrosion is similar to that of glass and is the highest of any metal in common use. Tantalum's extreme resistance to corrosion and heat make it a critical industrial metal for applications in high-temperature oxidizing environments like linings of nuclear reactors, aircraft components, rocket engines, vacuum furnace and heat exchanger installations, and chemical processing equipment.
The most common commercial use of metallic tantalum is in the compact, high-performance capacitors of electronics such as mobile devices, digital cameras, laptop computers, pacemakers, GPS systems, and anti-lock braking systems. Other applications for tantalum have emerged in advanced technology. Lithium tantalate (LiTaO3) is a ferroelectric perovskite crystal used in non-linear optics, and the high refractive index of tantalum oxide is utilized in optical coatings and metallic glass. In addition, the metal's excellent resistance to corrosion and heat make it an attractive cost-effective alternative to platinum or gold in fuel cell collector plates and in the extreme environments required for production of alternative energy sources like biofuels.
Tantalum: Tantalum is chiefly obtained as a by-product of tin processing, although it is also mined from the minerals columbite, tantalite and samarskite.
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25. Dubnium - About Dubnium: Dubnium, a synthetic chemical element with the symbol Db and atomic number 105, has a history steeped in international rivalry and scientific discovery. The element was first synthesized in the 1960s by research teams in California, USA, and in Dubna, Russia, then part of the former Soviet Union. This simultaneous discovery led to a prolonged dispute over the naming rights for the element, a controversy that lasted for 37 years and is often referred to as the "Transfermium Wars". This term refers to the contentious debates over the naming of the elements following fermium (element 100) on the periodic table.
The conflict was finally resolved in 1997 when the International Union of Pure and Applied Chemistry (IUPAC) officially named the element "Dubnium" in honor of the city of Dubna, home to the Joint Institute for Nuclear Research. This decision was seen as a compromise, acknowledging the significant contributions of the Russian research team to the discovery of the element.
Despite its fascinating history, Dubnium is a highly unstable and radioactive element with no known commercial applications. Its primary use is in scientific research, where it continues to contribute to our understanding of the properties of superheavy elements.
Dubnium: Dubnium is a synthetic element and is not found naturally. It is produced by bombarding californium-249 with nitrogen-15 nuclei.
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26. Chromium - About Chromium: In 1797, Louis Nicolas Vauquelin, a French chemist, received a sample of Siberian red lead, a mineral now known as crocoite. Despite its use as a pigment for over thirty years, the chemical composition of crocoite had been a matter of debate. Vauquelin ended this dispute by isolating a new metallic element, chromium, from the sample. The isolation process resulted in a variety of brightly colored solutions and compounds, leading to the element's name, derived from the Greek word "chroma" for "color". Vauquelin discovered traces of chromium in precious gems like rubies and emeralds, correctly hypothesizing that chromium was responsible for their vibrant colors.
Chromium's early applications took advantage of its compounds. Lead chromate, the primary compound in crocoite, was used to create a pigment known as "chrome yellow". This color is famous for its use on school buses in the United States and postal vehicles in some European countries. Although the use of actual lead chromate has significantly decreased due to toxicity concerns, the color is still replicated using safer alternatives. Viridian, a green pigment made from chromium(III) oxide, is non-toxic and is widely used in ceramics and glassware. Other chromium(III) compounds have been used in leather tanning since the early 19th century, as a reaction between chromium and collagen fibers stabilizes the leather.
Chromium compounds are still widely used in industry. They are used as catalysts in several chemical processes, including the production of polyethylene, the most common plastic. Chromium salts are used in wood preservatives, and chromium gives color to synthetic rubies and emeralds. The first laser was built using a synthetic ruby. Both chromite and chromium(III) oxide can withstand high temperatures and are often used as refractory materials like brick molds and foundry sands. Chromium (IV) oxide is magnetic and is used to manufacture the magnetic tape in audio cassettes.
Most chromium is used in metalworking, either as a component of alloys or in various surface treatments. Chromium strengthens alloys and provides corrosion resistance. High-speed tool steels include small amounts of chromium for added strength, while larger amounts of chromium produce stainless steel. Nickel-based superalloys, often found in devices like jet engines that require materials to be stable and strong at high temperatures, gain increased strength from chromium. Chromium can be applied to metal surfaces via electroplating, providing wear resistance and a decorative, silvery sheen. Chromic acid is used in chromate conversion coating, which produces a distinctive yellow finish on metal surfaces used for corrosion inhibition or as a primer for further coatings. Anodization of aluminum is another finishing process that uses chromic acid, although it does not produce a chromium-containing coating.
However, chromium(VI), also known as hexavalent chromium, is a potent carcinogen. Hexavalent chromium ions are strong oxidizing agents that can easily enter cells and cause significant damage to DNA and proteins. Many industrial processes that involve chromium, including chrome plating and chromium conversion coating, typically use hexavalent forms of chromium. This has led to a major environmental problem: the contamination of groundwater with hexavalent chromium from industrial waste. Alternative processes using trivalent chromium, which is not as toxic, are being investigated, as the use and disposal of hexavalent chromium are now heavily regulated.
Chromium is mined as chromite, an iron chromium oxide mineral. This ore can be processed into pure chromium metal or ferrochrome, an iron-chrome alloy primarily used in the production of stainless steel. Chromium can also be recovered from scrap, and recycled metal accounts for nearly a third of the chromium used annually.
Chromium: Chromium is found in the mineral chromite.
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27. Molybdenum - About Molybdenum: Molybdenum, a silvery-gray transition metal, is valued for its chemical and physical properties across various industries, including defense, avionics, metallurgy, glassmaking, pigments and dyes, organometallic chemistry, and the manufacturing of photovoltaics and semiconductor devices. As one of the refractory metals, molybdenum shares properties such as extremely high melting points and thermal conductivity, low thermal expansion and vapor pressure, excellent dimensional stability and creep resistance, and resistance to oxidation. Its chemical behavior is akin to tungsten. Despite having the sixth highest melting point of all elements and one of the lowest coefficients of thermal expansion among commercial metals, molybdenum's density is only 25% higher than iron. It ranks as the 54th most abundant element in the earth's crust but does not occur naturally, instead existing in oxide forms with various valence states. Molybdenum-containing minerals, including molybdenite (molybdenum sulfide), wulfenite (lead molybdate), and powellite, are commercially mined to produce the metal, as well as through the production of tungsten and copper.
Historically, molybdenum-containing minerals were often mistaken for lead due to confusion between lead sulfide and molybdenum sulfides. The element's name, derived from the Ancient Greek word for lead, "molybdos," reflects this confusion. In 1778, Carl Wilhelm Scheele identified the element by producing molybdenum oxide from molybdenite, naming it "terra molybdaenae". Peter Jacob Hjelm later yielded the metal in 1781 by heating linseed oil and carbon combined with molybdic acid.
While toxic in high amounts, molybdenum plays a crucial biological role as a cofactor required for enzyme function. It didn't play a significant commercial role until its use in German artillery during World War II. Since then, its role as an alloying agent has accounted for more than 75% of its usage. Often referred to as "moly," it offers numerous advantages including increased hardness, strength, creep resistance, resistance to wear and corrosion, weldability, and stability in high stress, high temperature environments. Molybdenum alloys, including Hastelloys, ferromolybdenum, Titanium-Zirconium-Molybdenum (TZM), and Molybdenum-Lanthanum (lanthanated moly, or MoLa), are used in various applications such as x-ray tubes, forging tools, and more. Commercial products that benefit from the use of molybdenum include armor, aircraft engine components, glass melting electrodes, valves, boiler plates, ribbons and wires for lighting, semiconductor base plates, hot-zones and heat sinks, sputtering targets for photovoltaic cell coatings and flat screens, crucibles for sapphire growth, circuit inks, and microwave devices. The isotope Molybdenum-99 is also used in nuclear imaging.
Molybdenum compounds serve as industrial catalysts for various processes, including the removal of sulfide compounds from crude oil, converting water to hydrogen gas, producing formaldehyde and acrylonitrile, and acting as a photocatalyst in the case of the n-type semiconductor molybdenum trioxide. Other applications include lubricants and pigments. Molybdenum disulfide and molybdenum diselenide can form two-dimensional thin films analogous to those of carbon (in the form of graphene) for use in flexible electronics. Electrodes composed of MoS2-graphene nanosheet composites significantly improve the performance of next-generation sodium air batteries.
Molybdenum: Molybdenum is found in the minerals molybdenite, wulfenite, and powellite.
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28. Tungsten - About Tungsten: Tungsten, a hard and extremely dense metal, is known for its resistance to heat. This steel gray to silvery white metal is indeed heavy, living up to its Swedish name, "tung sten," meaning "heavy stone." Tungsten's most remarkable characteristic is its high melting point, the highest of any metal, which is even higher than the temperatures at which metals like aluminum would vaporize. Its boiling point is roughly equal to the temperature of the sun's surface. Among all metals, tungsten also exhibits the highest tensile strength, lowest coefficient of linear thermal expansion, and lowest vapor pressure at elevated temperatures. Tungsten metal is electrically conductive and possesses outstanding mechanical damping capability, extremely high resistance to corrosion, high moduli of elasticity and compression, excellent creep resistance, and the ability to absorb x-ray and gamma ray radiation.
Tungsten is the heaviest element with a known biological function, used by some enzymes, and is not harmful to humans and animals in quantities typically encountered in the environment. The main mineral sources of tungsten are scheelite and wolframite, with other less common minerals including ferberite and hubnerite. Despite its assets, raw tungsten contains impurities that make it extremely brittle and difficult to machine. However, producing ultra-high purity tungsten increases its malleability and ductility while retaining its thermal stability, as does alloying it with other metals such as rhenium.
Tungsten's high melting point made it an attractive material for use in early incandescent lamps. Overcoming the difficulty of drawing it into flexible wires was a challenge until 1909 when GE researcher William D. Coolidge developed a revolutionary process for producing ductile tungsten filaments. This opened the door for the wide use of tungsten filaments in television tubes and cathode ray tubes.
Tungsten has applications in numerous industries and fields of study. The metal and its alloys are the choice material for high temperature, high pressure environments. Tungsten compounds play a role in advanced optoelectronics, thermosolar cells, and other cutting-edge high technology applications. Thin films of tungsten oxide can be used as a component of smart windows; cadmium tungstate is a phosphor material used in light-emitting diodes. Tungsten diselenide (WSe2) and tungsten disulfide (WS2) belong to a group known as transition metal dichalcogenides (TMDs or TMDCs) that have gained attention in recent years for their ability to form two-dimensional 1-atom thick monolayers similar to graphene but with a larger band gap. Tungsten diselenide has been used to create an n-type field-effect-transistor (FET), demonstrating the potential for future low-power and high-performance tungsten-based integrated circuits.
Tungsten: Tungsten primarily occurs in the minerals scheelite and wolframite.
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29. Seaborgium - About Seaborgium: Seaborgium, a member of the transactinide series, holds the distinction of being the heaviest element ever studied in an aqueous solution. This synthetic element first came into existence in June 1974 at the Joint Institute for Nuclear Research in the former Soviet Union. Later that year, a team at the Lawrence Berkeley National Laboratory also managed to produce the element.
Despite the Soviet team's initial discovery, the element was named after the American chemist Glenn Seaborg as part of a compromise agreement over the naming of elements 104 through 108. A Nobel laureate in Chemistry in 1951 and co-discoverer of 10 transuranic elements, Seaborg's concept of actinides revolutionized the periodic table. He also served a decade-long tenure as the chairman of the United States Atomic Energy Commission and was a passionate advocate for science education and literacy throughout his life.
The production of seaborgium atoms has been limited, with all isotopes having very short half-lives. This makes seaborgium one of the most challenging elements to study. As of now, the element has no known practical applications.
Seaborgium: Seaborgium is a synthetic element and is not found naturally. It is obtained by the particle bombardment of curium or californium.
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30. Manganese - About Manganese: Manganese, a brittle and hard paramagnetic metal, is prone to oxidation and is predominantly found as manganese dioxide. This black mineral was historically referred to as magnes, magnesia, or magnesia negra, names that originated from the Magnesia region in what is now known as Greece.
The dark hue of manganese dioxide made it a popular choice for pigments, a usage that traces back to Stone Age cave paintings. Manganese compounds were employed by ancient Egyptian and Roman glassmakers to color or decolorize glass, a practice that persists today. The use of manganese dioxide in glassmaking made it readily available for alchemists and early chemists, who used it to produce chlorine-based bleaching agents and other valuable laboratory reagents. While some of these chemists realized that the compound contained a new element, it was Johan Gottlieb Gahn who first isolated manganese metal in 1774. Spartan steel weapons, known for their exceptional hardness, had a high manganese content. Whether this was intentional or a result of working with manganese-rich ores is still debated. However, the impact of manganese on the hardness of steel was rediscovered in the early 19th century, leading to its widespread use in steelmaking.
Manganese continues to play a crucial role in alloy production. It is used in corrosion-resistant mixtures such as stainless steel and is added to enhance workability and tensile strength. In aluminum alloys, manganese is primarily added to prevent corrosion. Manganese can also be used as a finishing coating on ferrous metal objects through a process known as phosphating. In this process, manganese salts are dissolved in a phosphoric acid solution, and the object to be coated is submerged in the liquid, resulting in a thin layer of magnesium on the surface. This coating provides corrosion resistance and is often used in conjunction with additional coatings or paint.
Beyond metalworking, the most significant use of manganese is in batteries. Manganese dioxide was first used in the Leclanche cell battery design in 1866, powering early telegraphy and signaling devices. This compound is still used in modern zinc-carbon and alkaline batteries.
Manganese has several other notable properties that have led to various uses. Due to the wide range of possible oxidation states for the element, manganese compounds can exhibit a variety of colors, many of which have been used as pigments. Additionally, many manganese compounds are strong oxidizing agents and have been used in organic synthesis and industrial applications. Manganese oxide has been used in glassmaking to oxidize iron contaminants that would otherwise give the final product a green tinge. Potassium permanganate is used in water treatment to react with and remove iron and hydrogen sulfide contamination and can also be used as an antiseptic. Methylcyclopentadienyl manganese tricarbonyl is an organometallic compound used to increase the octane rating of gasoline and reduce engine knocking.
Manganese is a key component of several materials with unique electromagnetic properties that could be useful for new technologies. Manganese-based perovskite oxides exhibit colossal magnetoresistance (CMR), a phenomenon where the material's electrical resistance changes by orders of magnitude when exposed to a magnetic field. Magnetoresistance is currently used in technologies such as computer hard drives, but current materials show a much smaller change in resistance than is seen with CMR. Research into CMR aims to eventually use it to enhance current technologies. Manganese can also be a component of magnetic semiconducting materials such as gallium manganese arsenide, which have applications in fields such as spintronics.
Manganese is an essential trace nutrient for all known forms of life because it serves as a cofactor for many essential metabolic enzymes. However, an excess of manganese, particularly in certain forms such as inhaled dusts and fumes, can be toxic.
The primary ore of manganese is pyrolusite, the mineral form of manganese dioxide. This and other manganese ores are leached with sulfuric acid to extract manganese in solution, which is then purified using an electrowinning process to produce pure manganese. Alternatively, manganese ores can be combined with other ores and carbon in a blast furnace to produce ferromanganese or silicomanganese.
Manganese: Manganese is found in several minerals, including pyrolusite (MnO2), psilomelane (BaMn9O16(OH)4), rhodochrosite (MnCO3), and hausmannite (Mn3O4).
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31. Technetium - About Technetium: By the dawn of the 20th century, the modern periodic table had largely been established. However, a few gaps remained, including the position for element 43, which had a long and complex history. Since 1828, numerous researchers claimed to have isolated this new element, but all these claims were eventually debunked.
Theoretical work eventually provided an explanation for these repeated failures, revealing that element 43 would be unstable and thus impossible to isolate in significant quantities from natural sources. This led to laboratory attempts to produce element 43, culminating in the successful efforts of Italian chemists Carlo Perrier and Emilo Segre in December 1936. Consequently, technetium became the first element to be artificially produced and remains the only element ever discovered in Italy.
Technetium, despite its useful chemical properties, including its ability to protect steel from corrosion in aqueous solutions, has its applications limited due to its radioactivity. The primary uses of the element are related to its radioactivity. Technetium-99m, a short-lived gamma-emitter and a medical isomer of technetium-99, is medically useful as it can be bound to various compounds used by the body. It is routinely used in medical imaging of various organ systems. Technetium-99, on the other hand, decays slowly by emitting only beta particles and is used as a standard beta emitter for equipment calibration. This isotope also has potential for use in specialized applications such as nuclear batteries.
Technetium-99 is regularly produced as a component of radioactive waste from nuclear power plants, from which it can be isolated. Technetium-99m, having a very short half-life, must be produced from the radioactive decay of molybdenum-99, which is produced by irradiating uranium in dedicated reactors.
Technetium: Technetium does not exist in the Earth's crust, nor is it found in any mineral. Currently, it is only produced by artificial nuclear fission reactions.
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32. Rhenium - About Rhenium: The early 20th century marked a significant milestone in the evolution of the modern periodic table. The majority of chemical discoveries required nuclear reactors, shifting away from the traditional chemist's meticulous examination and chemical analysis of unique ores. However, a few gaps remained in the table, specifically elements 43 and 75, which were later filled with laboratory-produced radioactive elements.
These elusive elements, predicted by Mendeleev and named ekamanganese and dwimanganese, remained undiscovered until 1924. In this year, German chemists Walter Noddack and Ida Tacke, who later married, along with Otto Berg, claimed to have found these missing elements in platinum ores, based on spectral data. They named element 43 "masurian" after Noddack's birthplace in the Masurian marshes district, and element 75 "rhenium" after Tacke's birthplace in Rhenany-Rhineland. Regrettably, they could only isolate substantial quantities of rhenium. Subsequent theories suggested that element 43 would be too unstable to occur naturally, leading to widespread skepticism towards Tacke and Noddack's scientific credibility, despite their confirmed discovery of rhenium.
The initial extraction and purification process for rhenium, a rare element, was complex and costly, delaying its industrial application. Even today, its use is restricted by its limited availability and is primarily employed where small amounts can yield significant benefits. One such application is as an alloy additive: rhenium is a component of numerous heat-resistant superalloys. Nickel-based superalloys, valued for their high creep resistance, are commonly used in jet engines. Tungsten-rhenium and molybdenum-rhenium are utilized in thermocouples, typically for sensing extremely high temperatures. Rhenium-containing alloys may also be used in crucibles, self-cleaning electrical contacts, electromagnets, ionization gauges, and mass spectrographs. Another major application of rhenium is as a catalyst in petroleum processing, in catalytic converters alongside platinum, and in several niche or emerging applications. Additionally, Re-188 and Re-186 are used in cancer radiotherapy.
Rhenium is typically found in small quantities in molybdenum deposits and is obtained through the processing of molybdenum concentrates. Platinum-rhenium catalysts and rhenium alloy scrap are also frequently recycled.
Rhenium: Rhenium is generally obtained from molybdenite in porphyry copper mines and recovered as a by-product of molybdenum processing. Top producers of rhenium include Chile, Poland, the United States, and Uzbekistan.
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33. Bohrium - About Bohrium: Bohrium, a man-made element, presents a significant challenge for scientific study due to its extremely fleeting half-life. Its official discovery traces back to 1981 at the Institute for Heavy Ion Research (Gesellschaft fur Schwerionenforschung) in Germany, where scientists bombarded bismuth-209 with chromium-54. However, it wasn't until 2000 that an international team managed to produce quantities of Bohrium substantial enough for its chemical properties to be examined. The heaviest isotopes of Bohrium exhibit the slowest decay rates, with the longest measured isotope barely surpassing the 60-second mark. The element's low stability restricts its usage to fundamental scientific research. The element was named Bohrium in honor of the Danish physicist Niels Bohr, whose groundbreaking work on atomic structure forms the bedrock of atomic physics.
Bohrium: Bohrium is obtained by the fusion process of bombarding bismuth with chromium.
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34. Iron - About Iron: Iron, the most abundant element on Earth, forms the core of our planet and is the fourth most common element in the crust. This transition metal has been known since antiquity, with meteoric iron being the only source of the element in metallic form until around 1500 BCE. The advent of iron smelting techniques marked the beginning of the Iron Age, a significant technological advancement, as the production of iron metal from ore required higher temperatures than those used for bronze and pottery.
Pure metallic iron is quite soft, but the inclusion of carbon during the production process from ore significantly alters its properties. The earliest iron products were made from wrought iron, which contained less than one percent carbon. This material was tough, malleable, ductile, easily welded, and suitable for making general-purpose tools. However, it contained many impurities, had low tensile strength, and required considerable effort to shape into functional objects. The development of furnaces capable of melting iron led to the production of cast iron, which, due to its higher carbon content, was too brittle for use in weapons or tools that would sustain impact. However, it was more resistant to rust than wrought iron and could be easily cast into desired shapes.
The early forms of ironworking are now largely obsolete, although traditional cast iron is still used for cookware. Ductile iron, a related product engineered to be less brittle, is often used for water and sewer lines. The full potential of iron is realized through careful control of its composition, which allows for the production of alloys with a wide range of properties. Most ferrous alloys in common use are steels, primarily iron with a carbon composition between 0.002 and 2.1 percent, resulting in a product that is neither too soft nor too brittle. Steel production dates back as far as 4000 years ago, and by 500-400 BCE, cultures around the world were producing the metal regularly. However, the methods used were labor-intensive and costly, and the metal was used only when there was no alternative. It wasn't until the introduction of the Bessemer process in 1855 that steel was produced cheaply and in the large quantities necessary for modern industry.
Today, hundreds of varieties of steels are produced for various applications. Simple carbon steel, consisting only of iron and carbon, is sufficient for many uses, from structural applications to springs and high-strength wires. The addition of other elements provides many advantages. Low alloy steel contains ten percent or less of elements other than iron and carbon, usually added to improve hardenability. Stainless steels contain at least eleven percent chromium, sometimes along with other elements, and are designed to resist corrosion. Many other specialty steels exist, including tool steels, which include large amounts of tungsten or cobalt and can maintain a long-lasting sharp edge, and Cor-ten, a steel that weathers to a uniform rusted surface that is stable without surface treatments.
Iron is also used to produce magnets. Ferrite magnets are non-conductive magnetic ceramics made of iron oxide and are frequently used in transformers, electromagnets, and radios. Neodymium-iron-boron magnets are the strongest permanent magnets known and are used in motors, hard-disk drives, and magnetic fasteners. Before the development of such rare earth magnets, the strongest known magnets were alloys of iron, nickel, aluminum, and cobalt known as Alnico magnets. These are still used widely in almost any application where strong permanent magnets are needed, but increasingly neodymium magnets are used when their higher strength for a given size is a more important factor than their increased cost. Additionally, iron nanoparticles can be suspended in liquid to produce magnetic suspensions known as ferrofluids; these are used widely in ferrofluidic seals.
In addition to use in alloys and magnets, iron is commonly used in the form of compounds. Prussian blue, one of the first synthetic pigments produced, is an iron compound with a complex structure, and its brilliant color results from the presence of iron in multiple oxidation states. It is used widely in blue and black inks and paints, and produces the familiar blue of blueprints. Iron chloride is used in water treatment, as a catalyst, and to etch copper as part of the production of printed circuit boards. Iron pyrite, also known as fool's gold, is a semiconductor that is of interest for use in photovoltaic devices, though crystal defects in the material as commonly grown have presented a challenge for researchers. Iron is also a vital trace nutrient and is frequently used as a nutritional supplement, often in the form of iron sulfate.
Though iron silicates and carbonates are more common natural sources of the metal, all industrial sources are iron oxide ores, as the metal can be more easily extracted from these ores than more common forms. The highest quality deposits are hematite, which can be up to seventy percent iron, but some magnetite ores are also economically feasible iron sources.
Iron: Iron is found in many minerals, including magnetite, hematite, goethite, limonite, siderite, and pyrite. It is also found in many other minerals in smaller quantities.
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35. Ruthenium - About Ruthenium: Ruthenium, discovered in 1844 by Karl Ernst Claus, was named after Ruthenia, the Latin term for Claus's homeland, Rus. It was the last element of the platinum group to be officially discovered. Like its group members, ruthenium is known for its hardness and resistance to corrosion. In fact, ruthenium is harder than both platinum and palladium and, like the more costly rhodium, can be used to harden alloys of these elements. Thin coatings of platinum-ruthenium and palladium-ruthenium alloys are often used to make electrical contacts resistant to wear. Furthermore, ruthenium is added to titanium to provide corrosion resistance and is used in high-temperature single-crystal superalloys, most commonly in aerospace applications. Ruthenium is also compatible with vapor deposition for producing thin films and is being explored for use in microelectronics.
In addition to its roles in metallic form, ruthenium has many applications in the form of its compounds. Ruthenium dioxide and organometallic ruthenium complexes are used as catalysts in research, organic and pharmaceutical chemistry, and industrial settings. Ruthenium-based dyes have applications as biological stains for light and electron microscopy and are used in some dye-sensitized solar cells. The oils in fingerprints react with ruthenium tetroxide to produce darkly colored ruthenium dioxide, a process used to reveal latent prints.
Lastly, ruthenium has a few medical applications. A radioactive isotope of ruthenium is used in radiotherapy for eye tumors, and several ruthenium-centered complexes are being investigated for their anticancer properties.
Like other platinum group metals, ruthenium is typically obtained for commercial use as a byproduct of nickel and copper mining and processing. It can also be obtained from platinum-rich ores and alluvial deposits. Along with rhodium and palladium, ruthenium is a decomposition product of uranium and could theoretically be recovered from spent nuclear fuel. However, the challenges associated with handling radioactive materials make this an impractical source for this rare element.
Ruthenium: The main sources of ruthenium are the Merensky Reef of the Bushveld Complex, South Africa; the nickel-copper sulfide deposits of the Norilsk region, Russia and of the Sudbury region, Canada, and the Stillwater Complex, USA.
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36. Osmium - About Osmium: Osmium, a unique element, was first discovered in the form of osmium tetroxide (OsO4). The name 'osmium' is derived from the Greek word 'osme', which translates to 'a smell'. This name was chosen due to the strong odor emitted by osmium tetroxide. This compound forms spontaneously when pure osmium metal comes into contact with air. It is both volatile and extremely toxic, which is why the pure metal is seldom used.
However, osmium holds the distinction of being the densest naturally occurring element. It imparts hardness when incorporated into metal alloys. Alloys containing osmium are highly resistant to wear and tear caused by friction or frequent use. This makes them ideal for use in the tips of fountain pens, instrument pivots, and electrical contacts.
Despite its high toxicity, osmium tetroxide is the most commonly used osmium compound. It plays a crucial role in the life sciences, particularly for staining and fixing biological tissue for electron microscopy. It provides the necessary contrast when imaging substances primarily composed of carbon. It is also used as a lipid stain in light microscopy and, in some instances, for fingerprint detection.
Osmium tetroxide is highly valued as a chemical catalyst in Sharpless asymmetric dihydroxylation, a reaction that earned Karl Barry Sharpless the Nobel Prize in Chemistry in 2001. Although the cost of the compound somewhat limits its use, it is considered a far superior catalyst for this process compared to the alternative, KMnO4. Organometallic complexes containing osmium are currently being explored for potential use in cancer treatment.
Like other metals in the platinum group, osmium is typically procured for commercial use as a byproduct of nickel and copper mining and processing. However, it can also be obtained from platinum-rich ores and alluvial deposits.
Osmium: Osmium is found in its pure native form and in osmiridium, a natural alloy of iridium and osmium. It is mined from sulfide layers in mafic igneous rocks where it is present with other platinum-group elements. Most osmium is mined in Canada, Russia, and South Africa.
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37. Hassium - About Hassium: Hassium, with an atomic number of 108, is a synthetic element that falls under the category of transactinides. Initial experiments in the late 1970s by the Russian researchers Turi Oganessian and Vladimir Utyonkov at the Joint Institute for Nuclear Research aimed to isolate this element. However, the data available from these experiments does not conclusively establish their success.
The official discovery of Hassium is attributed to the German scientists Peter Armbruster and Gottfried Munzenberg at the Institute for Heavy Ion Research in 1984. The process of naming this element was fraught with controversy and was only resolved in 1997. The International Union of Pure and Applied Chemistry (IUPAC) eventually agreed to the discovering team's proposal to name the element after the German state of Hessen, which is home to the Institute for Heavy Ion Research (GSI).
Due to its instability, Hassium has not been extensively studied. However, its position on the periodic table allows for predictions about its chemical properties. As a Group 8 element, it is expected to share similarities with the platinum group elements, particularly osmium, its closest homologue. Interestingly, Hassium is predicted to have a density that surpasses all known elements, nearly doubling the density of osmium, the element with the highest measured density. Despite its instability, Hassium is a subject of extensive study in basic science research. However, it currently does not have any practical applications.
Hassium: Hassium is obtained by the fusion process of bombarding lead with iron.
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38. Cobalt - About Cobalt: Cobalt, a metal discovered by Swedish chemist Georg Brandt around 1935, has a rich history and a wide array of applications. Its ores, initially a source of frustration for miners due to their failure to yield expected metals and their production of toxic arsenic oxide when smelted, were named after kobolds - goblins blamed by German miners for mining mishaps.
Brandt not only discovered cobalt but also revealed that cobalt compounds had been unknowingly used since the middle ages to color smalt, a type of blue glass. By the late eighteenth and early nineteenth century, cobalt-based green and blue pigments were developed and widely used for coloring ceramics, jewelry, and paint. Today, while these applications remain relevant, cobalt is primarily used in its metallic form.
In the United States, the majority of cobalt is consumed in the production of superalloys. These metal formulations are often used in areas requiring resistance to extreme conditions, such as jet engine components or high-speed drill bits. Superalloys are also used in biomedical implants like hip replacements. However, these implants must be monitored for wear, as metal nanoparticles produced can be absorbed by and distributed throughout the body. Cobalt is also an essential nutrient found in cobalamin, or vitamin B12, but excess free cobalt ions in the body can have toxic effects.
Cobalt finds use in other alloy applications as well. It is a component of both Alnico and samarium-cobalt magnets, which are widely used in industry. Cobalt is also combined with primary electrode metals in lithium-ion, nickel-cadmium, and nickel-metal hydride batteries. Its attractive appearance, extreme hardness, and resistance to oxidation make it suitable for plating other materials, either alone or as a base for further coatings such as porcelain enamels. Platinum used in jewelry making contains five percent cobalt to produce an alloy suitable for highly detailed casting.
Cobalt serves two other major roles in industry. First, as a catalyst, cobalt compounds are used to produce polymer precursors, remove sulfurous impurities from petroleum, and improve the adhesion of steel to rubber in the production of steel-belted tires. Cobalt catalysts are also added as drying agents to paints and varnishes and used in various other chemical processes. Second, cobalt is used as a binder in cemented carbides, extremely hard materials used in machining metals like steel.
Cobalt radioisotopes also have notable uses. Cobalt-60, a radioactive isotope, is used to produce gamma rays for sterilizing food and medical supplies, in medical radiotherapy, and in the production of industrial radiographs. Cobalt-57 is used as a tracer in medical imaging, primarily for observing vitamin B12 uptake.
The main cobalt ores - cobaltite, erythrite, glaucodot, and skutterudite - are commercially exploited. However, a significant amount of the metal is also obtained from the processing byproducts of copper and nickel mining. Cobalt catalysts and cobalt-alloy scrap may also be recycled to recover high purity cobalt.
Cobalt: Cobalt is generally obtained from the minerals cobaltite and smaltite (cobalt arsenide). Other cobalt-bearing minerals include erythrite, glaucodot, and linnaeite (cobalt sulfide). Principal cobalt-producing countries include Congo (Kinshasa), Russia, Australia, Philippines, Cuba, Madagascar, and Canada.
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39. Rhodium - About Rhodium: Rhodium, a silver-hued, corrosion-resistant metal, is one of the rarest elements in the Earth's crust. Its scarcity, coupled with its numerous applications, contributes to its high cost. The majority of newly produced rhodium is utilized in the manufacture of three-way catalytic converters, where it outperforms other platinum group elements in reducing nitrogen oxides. Additionally, rhodium-based catalysts are extensively employed in industrial processes and various organic chemistry applications.
The remaining rhodium is used as an alloying agent to enhance the corrosion resistance and hardness of platinum and palladium, or for ornamental purposes. Alloys containing rhodium are used in spark plugs, advanced laboratory equipment, and thermocouples. In the jewelry industry, ultra-thin layers of this precious metal are electroplated onto white gold or platinum to create a reflective white surface, a technique known as "rhodium flashing".
Platinum, initially known as platina, arrived in Europe as grey metallic crumbs that were unworkable in their native form. Initially, only a few individuals could transform platina into usable platinum, and the process was a closely guarded secret. The inconsistency in the properties of the final material produced from early platina processing was resolved when it was discovered that platina comprised several different metals. English chemist William Hyde Wollaston was the first to isolate rhodium from platina samples, naming the element after the rose-red color of one of its compounds.
Like other platinum group metals, rhodium is typically obtained for commercial use as a byproduct of nickel and copper mining and processing. It can also be sourced from platinum-rich ores and alluvial deposits. Rhodium, along with ruthenium and palladium, is a decomposition product of uranium and could theoretically be recovered from spent nuclear fuel. However, the challenges associated with handling radioactive materials render this an impractical source for this rare element.
Rhodium: Rhodium is generally obtained as a byproduct of copper and nickel refining.
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40. Iridium - About Iridium: Iridium, a member of the platinum group metals, was first introduced to Europe as an unusable grey metallic substance known as platina. It was only when English chemist Smithson Tennant dissolved platina in aqua regia, a potent mixture of acids, that he discovered the dark insoluble residue contained two new elements: osmium and iridium. Tennant named iridium after Iris, the Greek goddess of rainbows, inspired by the vibrant colors of its salts.
Iridium stands out among the platinum group metals for its exceptional hardness, resistance to corrosion, and high melting temperature of 2466 degrees Celsius. These properties make iridium highly desirable in certain applications, but its hardness and brittleness make it difficult to work with, and its high melting point makes traditional casting impractical.
Despite these challenges, iridium finds use in a few key areas. Its primary use is in crucibles for high-temperature procedures, essential for producing high-purity single-crystal materials such as semiconductors, garnets for lasers and industrial welding, synthetic sapphire for electronics, silicate crystals for sensors, and lithium crystals for electronics.
Iridium also finds use in the encapsulation of plutonium-238 fuel in radioisotope thermoelectric generators for unmanned spacecraft, the production of antiprotons for particle physics experiments, and the production of mirrors for x-ray optics applications. Iridium radioisotopes are used for gamma-radiography for metal testing and some forms of medical radiotherapy.
In combination with other elements, iridium imparts increased hardness and resistance to corrosion and heat. These alloys find use in applications requiring materials that can withstand substantial wear or extreme conditions. Historical uses include fountain pen tips and cannon components, while modern applications include spark plug electrical contacts, microelectrodes for electrophysiology, and resilient aircraft engine parts. A platinum-iridium alloy was even used to construct the international prototype meter and kilogram mass in 1889, with the kilogram prototype still in use as the international standard for mass. Iridium compounds are frequently used as chemical catalysts in research and industry.
Like other platinum group metals, iridium is typically obtained as a byproduct from nickel and copper mining and processing, but can also be sourced from platinum-rich ores and alluvial deposits.
Iridium: Iridium is found in its pure native form and in osmiridium, a natural alloy of iridium and osmium. Iridium is mined from sulfide layers in mafic igneous rocks where it is present with other platinum-group elements. Most iridium is mined in Canada, Russia, and South Africa.
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41. Meitnerium - About Meitnerium: Meitnerium, a transactinide element, is not naturally occurring and is highly radioactive. It was first synthesized in 1982 by a research team at the GSI Helmholtz Centre for Heavy Ion Research in Germany. The team achieved this by bombarding a bismuth-209 target with accelerated iron-58 nuclei. The most stable known isotope of meitnerium has a half-life of a mere 7.6 seconds, which makes it too short-lived for practical applications or comprehensive chemical studies. Based on its position in the periodic table, it is anticipated to share properties with the platinum group metals.
The element is named in honor of Lise Meitner, an Austrian physicist who co-discovered nuclear fission, the element protactinium, and the Auger effect. Despite her significant contributions to science, Meitner's work was often overlooked during her lifetime (1878-1968). This likely influenced the International Union of Pure and Applied Chemistry's (IUPAC) decision to recommend naming the element after her in 1994, a recommendation that was officially adopted in 1997.
Meitnerium: This element is highly radioactive and has never been found naturally. It is obtained by the fusion process of bombarding bismuth with iron.
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42. Nickel - About Nickel: Nickel, despite its ubiquity, remained unrecognized as a distinct metal for centuries. It was present in every iron object produced before the Iron Age, as it was a component of meteorites, the sole source of iron before ore extraction became common. As far back as 1700 BCE, Chinese metalworkers were known for their skill in producing paktong, or white copper, a metal derived from local ores with a small addition of zinc for workability. However, the unique color of the alloy was not attributed to the high nickel content in the copper ores. Similarly, other ancient societies used naturally occurring copper-nickel ores for coinage but failed to distinguish the metal from pure copper.
The turning point came in 1751 when Baron Axel Fredrik Cronstedt extracted a white metal from a mineral known as kupfernickel. Medieval German miners, unable to extract copper from what they believed to be copper ore, had named this mineral kupfernickel, combining kupfer (copper) and nickel (an old name for the devil), whom they blamed for their misfortune. Consequently, the name Cronstedt gave to his newly discovered metal, nickel, referenced the host mineral and its mythologized demonic origins.
At the time of Cronstedt's discovery, the new metal was deemed as useless as the native ore from which it was extracted. However, this perception changed dramatically in 1823. Europeans had been importing the Chinese alloy "paktong" (cupronickel) for two centuries, and several German scientists finally managed to replicate it and develop a functional production process. This European version of cupronickel, known as German silver, nickel silver, and various trade names, was valued for its silver-like appearance, hardness, and corrosion resistance. It was used in both decorative and functional applications, including the production of silverware, musical instruments, plumbing fixtures, and coins. The exact formulation of copper-nickel alloys has varied over time and by application, but they are still widely used.
Today, attractive and functional alloys constitute the largest use of nickel. Nickel is a crucial component of certain types of stainless steel and cast iron, as well as some superalloys designed for extreme conditions. Additionally, Alnico alloys containing nickel are used to make strong permanent magnets for various industrial and consumer applications. Nickel is also commonly used as a thin layer plated on other metals through either electroplating or electroless methods. Both forms of nickel plating increase wear and corrosion resistance, as nickel is very hard and develops a thin oxide coating upon exposure to air, which prevents further corrosion. One notable use of the electroless process is in the production of hard-drive disks, where the nickel layer provides an extremely smooth surface for the deposition of magnetic recording layers.
Another significant use for nickel is in batteries and fuel cells. Various battery designs, including those utilizing nickel-cadmium, nickel-iron, nickel-hydrogen, and nickel-metal-hydride chemistry, use nickel as a cathode. In alkaline fuel cells, nickel foam or nickel mesh serve as gas diffusion electrodes. Furthermore, nickel or nickel alloys such as Raney nickel are used as catalysts in industrial chemistry and organic synthesis, and nickel is sometimes added to glasses or ceramic glazes to produce a bright green color.
Nickel is extracted from two types of ore deposits: laterites or magmatic sulfide deposits. The traditional roasting and reduction process used to refine nickel yields a metal of 75% or greater purity. While this relatively low purity may suffice for some applications such as stainless steel, various purification techniques are available to produce higher purity metals. The Mond process, used since the late nineteenth century, produces nickel metal of 4N purity or higher from nickel oxides.
Nickel: Nickel is generally found in two main types of deposits: from the mineral garnierite (Ni-silicate) in nickel-rich laterite formed by weathering of ultramafic rocks, and in Ni-sulfide concentrations, mainly from pentlandite in igneous mafic rocks.
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43. Palladium - About Palladium: Palladium, a member of the platinum-group metals, was discovered in 1802 by William Hyde Wollaston during his efforts to refine platina deposits into usable platinum. The newly discovered element was named after the asteroid Pallas, which was also a recent discovery at the time. Wollaston initially chose to market the element anonymously through an advertisement in 1803, but later officially announced his discovery in a scientific publication.
Like its platinum-group counterparts, palladium is a silvery, relatively non-reactive metal. However, it stands out within the group due to its lowest melting point and least density. Palladium finds its applications similar to platinum, serving as a catalyst and being used in the production of various products in its metallic form. It catalyzes processes such as petroleum cracking, water treatment, nitric acid production, and polymer manufacturing. It is also a key component in catalytic converters and fuel cells. Furthermore, palladium enhances the rate of hydrogenation and dehydrogenation reactions and plays specialized catalytic roles in organic chemistry. This led to the awarding of the 2010 Nobel Prize in Chemistry for the development of palladium-catalyzed reactions used in organic synthesis.
In its metallic form, palladium is utilized in electronics for component plating, electrical contacts, and solder. It is also used in jewelry, watches, blood sugar test strips, and surgical instruments. When alloyed with silver, it serves as electrodes in the production of multilayer ceramic capacitors. Both platinum and palladium salts find a niche use in the production of fine-art black and white photographic prints through the platinotype process.
Palladium exhibits unique chemical interactions with hydrogen, which are not shared with platinum. Hydrogen gas can easily diffuse through heated palladium, making it useful in the production of high purity hydrogen. Palladium also absorbs hydrogen gas to form palladium hydride, a property currently under research for potential applications in hydrogen storage. Palladium chloride is efficient in oxidizing carbon monoxide and is used in detectors for this toxic, odorless gas. Radioactive palladium is also being explored for potential use in cancer treatment.
Commercially, palladium is typically obtained as a byproduct from nickel and copper mining and processing. It can also be sourced from platinum-rich ores and alluvial deposits. Along with ruthenium and rhodium, palladium is a decomposition product of uranium and could theoretically be recovered from spent nuclear fuel. However, the challenges associated with handling radioactive materials make this an impractical source for this rare element.
Palladium: Palladium is generally found only in pure form, and along with platinum is found in sulfide concentrations in mafic igneous rocks. It is mined in Russia, the USA (Montana), Zimbabwe, Australia, Canada, and Finland.
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44. Platinum - About Platinum: Platinum, a platinum-group metal, has been utilized in the creation of gold-platinum alloy items by pre-Columbian natives of the Americas for over 2,000 years. However, it was not until the 18th century that platinum, in its native form known as platina, was introduced to Europe by Spanish explorers. The name platina, derived from the Spanish word for silver, plata, was eventually adopted as the official name of the element. Antonio de Ulloa is credited with the discovery of platina in 1735, but his involvement with the metal was limited to his initial report describing the metal in 1746. Subsequently, chemists across Europe began experimenting with this new metal.
In the 18th century, chemists recognized the potential value of platinum, a hard and corrosion-resistant metal, but faced challenges in producing malleable platinum from the ore. In 1751, Swedish scientist Henrik Scheffer discovered a method to fuse grains of platinum ore into malleable platinum by heating them in the presence of arsenic. This process was refined over the next fifty years, leading to the production of the first European products made from the metal. However, all these processes had some inconsistencies and required laborious or costly steps, limiting the production of the metal. During this period, platinum was primarily used for the production of ornamental pieces and laboratory ware.
In 1802, English chemists Smithson Tennant and William Hyde Wollaston collaborated to develop a more efficient method to produce workable platinum. They discovered that platinum ore contained trace amounts of several other elements previously unknown to science. This contamination led to variations in the properties of the produced "platinum". This new understanding facilitated the development of more reliable and efficient methods for processing platinum ore, leading to a boom in the availability and use of the metal.
In 1817, chemist Humphry Davy, while attempting to produce a lamp safe for use in coal mines, discovered the phenomenon of heterogeneous catalytic oxidation. He found that coal gas would burn without a flame and at a lower than usual temperature only when it came in contact with platinum or palladium metal wire. This discovery led to the identification of many reactions where platinum could serve as a catalyst. By the beginning of the 20th century, platinum catalysts were widely used in the industrial production of sulfuric and nitric acid.
Today, platinum catalysts are essential for catalytic converters, which reduce toxic emissions by automobiles, for petroleum processing, and for a wide range of organic synthesis applications. The 2007 Nobel Prize in Chemistry was awarded to Gerhard Ertl for his research on catalytic oxidation of carbon monoxide, the chemistry that underlies the function of catalytic converters. Additionally, two other Chemistry Nobel Prize winners investigated platinum catalysts in their research, though each was ultimately awarded the prize for processes that used other metals as catalysts. Paul Sabatier's award in 1912 recognized him for his work on hydrogenation reactions for which he ultimately found nickel metal to be more effective than platinum. The first successful production of ammonia from gaseous nitrogen was performed in 1881 using a platinum catalyst, and Fritz Haber's research into improving this process ultimately resulted in the Haber process for which he won the 1918 Nobel Prize. Haber's final process as used in industry used iron-based catalysts rather than platinum group metals, but his research would not have been possible without prior work using platinum.
While researchers investigated the chemical properties of platinum in the 19th century, the metal was also growing in popularity for use in jewelry manufacturing. Platinum is in some ways a better metal for jewelry than either silver or gold, as it is harder than either and does not tarnish like silver. Once several prominent jewelers started using the metal in the late 1800's, platinum rose rapidly in popularity, becoming particularly fashionable for the setting of colorless stones. This continued until 1940, when platinum use was restricted to industrial production of chemicals needed in the war effort. Platinum was replaced by white gold due to these restrictions, but has returned to popularity in recent years.
Platinum and platinum alloys are used in a wide range of settings where chemical inertness or wear resistance are important, including medical devices, laboratory instruments, electrical contacts, spark plugs, and turbine engines. A platinum-iridium alloy was also used to produce the international prototype kilogram and meter in the late 19th century; of the two only the kilogram remains in official use. Finally, organometallic platinum complexes have been investigated for use in cancer treatment.
Like other platinum group metals, platinum is most often obtained for commercial use as a byproduct from nickel and copper mining and processing, but can also be obtained from rare platinum-rich ores and alluvial deposits of native platinum.
Platinum: Platinum is present in thin sulfide layers in certain mafic igneous bodies. Platinum-group metals are mined in South Africa (top producer), Russia, Zimbabwe, Canada, and the United States.
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45. Darmstadtium - Darmstadtium is a super-heavy, radioactive element that is not found naturally and disintegrates within milliseconds of its synthesis. Prior to its synthesis, the element was temporarily referred to as ununnilium (Uun). In 1994, the isotope 269Ds was definitively synthesized at the GSI in Darmstadt, Germany. This was achieved by bombarding a lead target with nickel ions over several days. The team at GSI proposed the name darmstadtium in honor of the city of Darmstadt, a proposal that was accepted by the IUPAC. Due to its extreme instability, much about darmstadtium remains unknown, and it currently has no known commercial applications.
Darmstadtium: This element is highly radioactive and has never been found naturally. It is obtained by the fusion process of bombarding bismuth with nickel.
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46. Copper - About Copper: Copper, a soft, malleable, and highly conductive metal, has been utilized by human societies since ancient times. Before the discovery of copper around 9000 BCE, gold and meteoric iron were the only metals commonly used. The existence of native copper deposits, which could be worked cold due to the metal's softness, facilitated its early use. However, native copper is relatively rare, leading to the development of the smelting process for copper from ore, which inadvertently led to the discovery of alloying.
The addition of another metal to copper increases its hardness and casting ease, significantly enhancing the metal's utility. This was initially achieved through the smelting of copper ores containing small amounts of other metals, often arsenic and silicon, to produce a natural bronze. Later, it was discovered that bronze could be intentionally produced by adding tin to molten copper. This advancement occurred between 4500 BCE and 600 BCE in different regions of the world. The production of bronze is now recognized as such a key technological achievement that the period in any society between this discovery and the development of iron smelting is often referred to as the "Bronze Age".
The introduction of bronze allowed for the creation of harder, more durable metal tools and weapons. Bronze was so vital to civilizations of this period that history was shaped by the trade of the relatively rare tin ore necessary for its production. Although copper was easier to obtain, its sources were also significant to ancient societies, leading to the naming of the element. In the Roman Empire, copper was most often mined on the island of Cyprus, and the modern name of the metal is derived from the Latin "cuprum", which itself was derived from "cyprium", meaning "metal of Cyprus".
While for many uses, alloys have preferable properties to pure copper metal, architecture has made use of elemental copper since ancient times. The patina that the metal develops over time provides a natural coating that makes it extremely durable and low-maintenance, and its malleability lends it to being molded into desired shapes. Today, copper in architecture is most often seen in roofing, flashings, rain gutters, and downspouts.
Metals other than tin came into use for alloying with copper later in history, especially nickel and zinc. Brass, an alloy of zinc and copper, is more malleable than either individual metal, easier to cast, and has excellent acoustic properties. Initially, brass was used in coins and for decorative purposes, while today it is used extensively in brass musical instruments, for plumbing and electrical applications, and in applications such as locks where low metal-on-metal friction is required. Cupronickel alloys, including ancient Chinese paktong and European nickel silver or German silver, were initially used in a variety of applications, and still find use in the production of coins, plumbing fixtures, and musical instruments. Copper is also found in some gold alloys and in sterling silver.
In addition to using copper and its alloys widely for tools, instruments, currency, and building materials, ancient societies took advantage of copper for its antimicrobial properties. Though the ancient Egyptians did not understand that the copper was preventing the growth of microscopic organisms, they did recognize that water stored in copper vessels went foul less frequently, and that wounds dressed with copper tended to heal better. Today copper is still used in this capacity in a variety of settings, most notably hospitals, where coatings of copper on frequently-touched surfaces help to limit the spread of disease-causing organisms.
Current applications for copper make frequent use of one of its properties that was not of particular interest for most of our history: electrical conductivity. Copper can be easily drawn into wires, and is the preferred electrical conductor for most wiring applications-roughly half of all copper mined is used in this way. In addition to being highly conductive, copper has high tensile strength, low thermal expansion, and resists corrosion and creep, properties which together result in reliable circuitry. The high conductivity of copper also enhances the energy efficiency of electric motors. Copper is likewise found in electronic devices such as electromagnets, vacuum tubes, magnetrons, and microwaves. Heat sinks and heat exchangers in electronic devices also sometimes use copper, as it dissipates heat more quickly than the most common alternative, aluminum.
Copper compounds also have many notable uses. Copper oxides and carbonates are used in pigments and glassmaking, and copper sulfate can be used as an herbicide, fungicide, and pesticide, as well as a chemical reagent in organic synthesis. Several copper compounds are semiconductors, including copper (I) oxide, one of the materials in which many semiconductor applications were first investigated. Today, copper semiconductors mostly find use in thin film solar cells. Copper can also be a component of high-temperature superconductors, and copper is used frequently in organic synthesis as a catalyst.
Naturally-occurring metallic copper has at times played a significant role in commercial supply of the metal, but most copper is found in sulfide, carbonate, and oxide minerals. Copper sulfides are the major copper ore, and after separation from iron and other unwanted material, these are roasted to produce the oxide. Copper oxide is then converted to blister copper through heating, and further purified through electrorefining. Copper is also recyclable without any loss in quality, and is the third most recycled metal after iron and aluminum.
Copper: Copper is found in many minerals that occur in deposits large enough to mine. These include azurite, malachite, chalcocite, chalcopyrite, and bornite. Most copper comes from chalcopyrite.
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47. Silver - About Silver: Silver, one of the earliest known precious metals to mankind, has always been a highly prized material for coinage, jewelry, and decorative items. Its properties have also led to its extensive use in modern technology, although its relatively high cost often prompts the use of cheaper alternative materials. However, the availability of easily accessible silver reserves have led to its substitution for cheaper metals that are temporarily in short supply. Notably, during the world wars, silver reserves were utilized as substitutes for copper in electrical applications, tin in solder, and nickel in coin production.
Silver possesses the highest electrical conductivity of any element. While copper is a more economically viable substitute, for some applications the energy savings or performance benefits provided by the substitution of silver are substantial enough to overcome this cost barrier. Silver may be used for electronics applications in cases where other key physical or chemical properties are uniquely advantageous. For instance, silver nanowires can be used to produce transparent and flexible electrodes for use in photovoltaic solar cells, and silver nanoparticles and conductive silver inks are used in the production of RFID tags and membrane switches used for TV remote controls, computer keyboards, and control panels on home appliances. Silver cadmium oxide and other conductive silver compounds are favored for use in high-voltage contacts because they resist the effect of electrical arcing. Silver is also a component of some materials used for phase-change memory technologies such as rewritable optical discs (CD-RW).
Mirrors can be produced by a chemical process that coats glass with a thin layer of silver metal, often termed silvering, which was discovered in 1835. Today, standard mirrors are usually produced using sputtered thin coats of aluminum, as it is cheaper than silver and less subject to tarnishing. However, glass ornaments and some high-quality mirrors are still sometimes made with the silvering process. Thinner layers of silver are visually transparent but effectively block UV radiation; today, optical glass coated with such layers is used in energy-saving window panes. Film photography, first developed around the same time, still uses silver as an essential component of almost all film photography processes, which exploit the photosensitivity of silver halide compounds. Finally, silver ions are naturally germicidal, and silver and its compounds have been used in wound care and as a disinfectant for centuries. Today, silver is still found in antimicrobial creams for treating burns, and silver nanoparticles are used in water filtration systems and embedded in clothing to deter bacterial growth.
Several specialized battery formulations contain silver salts. Silver oxide batteries have a long working life and high energy-to-weight ratio, and therefore are used in small devices such as hearing aids. Silver-zinc batteries are likewise valued for high-energy density, as well as for being extremely safe and reliable, with a long life both on the shelf and in active use. Silver-zinc formulations are frequently used in batteries designed for aerospace and defense applications such as NASA launch vehicles, missiles, and satellites. As with the use of silver as a conductor for electronics, the use of these batteries is limited by the added expense of silver, but in some applications, the advantages are considered worth the cost.
An additional key use for silver is in silver soldering and brazing. Both are methods used to join metallic components, but they vary in the composition of the joining material and the temperatures required. Silver soldering is a lower-temperature process often used in jewelry making or as a substitute for lead-based solders, and often uses tin-silver or tin-silver-copper formulations. Silver brazing is a higher-temperature process that produces an extremely strong joint that will resist significant shock and vibration while using very small amounts of a silver brazing alloy. Brazing is used frequently for attaching cemented carbide tips to tools.
Silver staining procedures, which typically make use of soluble silver nitrate along with various sensitizers and fixatives, are used in biology labs, as silver ions bind tightly to most proteins and allow their visualization on diagnostic gels, in karyotypes, and in tissue samples. Silver is often included in nuclear control rods to absorb free neutrons and used to plate steel bearings for use in automotive or jet engines to reduce friction. Amalgam fillings made of mercury in combination with silver or gold are still used in dentistry, but increasingly ceramic composites are favored for cosmetic reasons and due to safety concerns related to the use of mercury. Silver also serves as a catalyst in the industrial production of ethylene oxide and formaldehyde or as one of several catalysts found in catalytic converters, but platinum group metals are usually preferred for this purpose.
Silver: Silver is typically found in two types of deposits: laterite deposits, which are the result of intensive weathering of surface nickel-rich rocks, and magmatic sulfide deposits.
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48. Gold - About Gold: Gold, a pure metallic element, is known for its unique properties: it is the most malleable and ductile of metals, has an unusual color for elements of that class, is mostly non-reactive, conducts electricity well, and is extremely dense. The density of gold contributes to its relative rarity, as gold present when the earth was formed would have largely sunk to the core of the planet. It is therefore believed that virtually all gold discovered by humans was deposited considerably later by meteorites containing the element. The low reactivity of gold explains why the metal was known to ancient societies despite its rarity: unlike most metals, it occurs mostly in its elemental form.
The rarity of gold, combined with the ease with which it can be worked, its visual distinctiveness, and its resistance to chemical corrosion, made it an extremely unusual material and the object of much fascination. It was an obvious choice, then, for use as an ornamental status symbol and as a unit of monetary exchange. The oldest gold artifacts known have been dated to the 4th millennium BC, and the first gold coins (actually made of electrum, a natural gold-silver alloy) were minted around 600 BC in present-day Turkey. Gold remained a major component of monetary systems for much of the world into the twentieth century, as even when gold coinage became less common, most industrial economies used a gold standard to back their currencies. Gold standards started to be abandoned during World War I, and over time all modern industrialized nations switched to fiat currency systems.
Despite the fall of gold from an official monetary function, it is still widely viewed as valuable and used as an investment metal or means of storage of wealth, with many hoarding it as a hedge against inflation, and gold also remains a common metal used in fine jewelry. These functions still consume the majority of gold produced, despite a large number of other applications for the metal. Amalgams of gold and mercury have long been used in restorative dentistry for fillings and crowns, though concerns of mercury toxicity and the increasing availability of suitable composite materials as replacements have led to a decline in demand. Gold also finds many applications in electronics, where its high conductivity makes it attractive for wiring or as a coating for more easily corroded metals. Printed circuit boards often feature such thin protective gold layers. Thin films of gold are also useful for a variety of other functions. Gold can be manufactured to be thin enough to appear transparent, and thus be used in windows-in settings such as aircraft windshields-that can then be de-iced by passing electricity through the conductive film. Gold films are also excellent reflectors of electromagnetic radiation, including infrared light and radio waves, and are therefore used in infrared mirrors, heat shielding, and protective coatings on satellites and other equipment.
Despite being known for its low reactivity, it has long been known that gold can be dissolved in nitro-hydrochloric acid (aqua regia) and will form some compounds, including gold chlorides, gold oxides, and thiosulfates (such as gold sodium thiosulfate), and many applications of gold involve these less-familiar forms. Gold chloride solutions prepared by dissolving gold in aqua regia have been used to produce cranberry glass, the brilliant red color of which is now known to come from nanoscale gold particles dispersed within the glass.
Suspensions of such gold particles in liquid, also known as colloidal gold, are now of great interest due to their unique optical and electrical properties, in addition to their potential for useful interactions with biological systems. The electromagnetic absorption of collodial gold solutions is tunable based on the size of the particles, a useful property with a side-effect of producing solutions that range in color from red to blue. Such solutions can be used in printable conductive inks for electronics, the production of sensors and photovoltaics, and the preparation of microscopy samples.
There is a significant history in modern biology of attaching tiny gold particles to a variety of biological probes, usually for use in electron microscopy, where the high electron-density of the gold particles makes them easy to visualize.Today, the ability to specifically target gold nanoparticles this way is being used in medicine, which prizes the ability to target specific tissues or cell types, including cancer cells. This allows them to be used in the detection of cancer cell locations and in the site-specific delivery of drugs and other therapeutic agents (including small RNA molecules under investigation for use as gene therapy). Additionally, gold nanorod structures absorb light in the near-infrared range, which easily passes through many human tissues. This fact has been exploited in cancer treatment: the heat generated when near-infrared light is absorbed by the rods kills the cells containing them, leaving surrounding cells largely unscathed.
Gold occurs most often as a native metal on its own or as natural gold-silver alloy. Most gold is mined in this form from either lode or placer deposits, and a small amount is produced as a byproduct of the processing of base metals. Additionally, gold is also frequently recycled from scrap, and many financial institutions still hold significant gold stockpiles.
Gold: Gold occurs in significant amounts in three main types of deposits: hydrothermal quartz veins and related deposits in metamorphic and igneous rocks; in volcanic-exhalative sulphide deposits; and in consolidated to unconsolidated placer deposits.
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49. Roentgenium - About Roentgenium: Roentgenium, a man-made super heavy element, was first created in 1994 at the Institute for Heavy Ion Research (Gesellschaft fur Schwerionenforschung (GSI)) in Darmstadt, Germany. In 2004, the International Union of Pure and Applied Chemistry (IUPAC) approved the name roentgenium for this element, in tribute to Wilhelm Conrad Rontgen. Rontgen, in 1895, identified x-rays as a distinct type of rays with unique properties that made them particularly useful in a range of applications. Roentgenium itself, however, has no commercial uses and much about its properties remains unknown due to its extremely short half-life.
Roentgenium: This element is highly radioactive and has never been found naturally. It is obtained by the fusion process of bombarding bismuth with nickel.
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50. Zinc - About Zinc: Zinc, a metal recognized for its versatility, was utilized in alloys by human societies long before it was identified as a distinct metal. The earliest brasses, which are alloys of copper and small amounts of zinc, were produced as far back as several millennia BCE. This likely occurred due to the accidental smelting of zinc-rich copper ores. By the eighth century BCE, the unique properties of metals smelted from such ores were recognized, making the ore highly valued and sought after.
Starting in the first century BCE, brass was manufactured by heating copper ore and zinc ore together, creating a zinc vapor that reacted with the copper. This period saw brass being widely used in coinage and military equipment, and the methods for its production spread globally. By the 14th century in India and the 17th century in China, metallic zinc was deliberately produced. Although various European chemists and alchemists worked with the metal, the discovery of zinc as an element is generally attributed to German chemist Andreas Marggraf for his extensive work in 1746, where he demonstrated his ability to obtain metallic zinc from several zinc compounds.
In contemporary times, zinc continues to be employed as an alloy metal. Brass alloys, more corrosion-resistant than copper and more workable than zinc alone or the other common copper alloy, bronze, are notable for their acoustic properties, making them suitable for use in musical instruments. Brass also retains some of the antimicrobial properties of copper, making it ideal for commonly touched objects in hospitals, including doorknobs and surfaces. Another alloy, "nickel silver," which contains nickel, copper, and zinc, is used decoratively and in many musical instruments that are silver in color. There are also many majority-zinc alloys tailored to specific uses, with small amounts of additives used to impart key qualities. For example, zinc-aluminum has a lower melting point and lower viscosity than zinc, making it more suitable for casting small and intricate shapes. Zinc sheet metals are produced using small amounts of titanium and copper, which make the resulting alloy less brittle than zinc and therefore can be roll formed or bent.
As significant as zinc alloys have been throughout history and continue to be today, in modern times, zinc's largest use is in galvanizing other metals, usually iron or steel, to protect them against corrosion. Galvanization involves the application of a thin coating of zinc to a metal surface through any of several methods. Initially, the top of this layer reacts with the atmosphere to produce zinc carbonate, which protects all the underlying metal from corrosion. However, when the zinc layer is scratched down to the underlying metal, zinc still protects the underlying metal by acting as a sacrificial anode. This same property is exploited when zinc is used as the sacrificial anode in cathodic protection of buried pipelines or submerged iron components of a ship. Zinc also serves as an anode in alkaline batteries, zinc-carbon batteries, silver-zinc batteries, and zinc-air fuel cells, and as a cathode in silver oxide batteries.
Numerous zinc compounds are used in everyday products such as deodorants, cosmetics, sunscreens, anti-dandruff shampoos, and dietary supplements. Some zinc compounds are used in organic synthesis or industrial chemistry: notably, zinc oxide has long been used as a catalyst in the vulcanization of rubber. Additionally, compounds of zinc with oxygen, sulfur, selenium, or tellurium are all II-VI semiconductors with properties that recommend them for a variety of optoelectronic applications, including light-emitting diodes (LEDs), laser diodes, and solar cells. Zinc sulfide, zinc selenide, and zinc telluride all are used as infrared or near-infrared optical materials, and doped versions of each compound exist with other useful properties such as scintillation. Zinc may also serve as a component of the ternary semiconductors cadmium zinc telluride and mercury zinc telluride, which are useful for similar applications, but additionally have band gaps that can be easily tuned by altering the precise composition of the material.
Zinc is the fourth most commonly used metal, trailing only iron, aluminum, and copper. It is primarily mined from zinc sulfide deposits, which are generally roasted to produce zinc oxide and then processed to the metal through pyrometallurgy or electrowinning. Most of the zinc used annually is newly mined, but about thirty percent is recycled.
Zinc: Zinc is primarily obtained from the minerals sphalerite (zinc blende), smithsonite, wurtzite, and hemimorphite.
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51. Cadmium - About Cadmium: Cadmium, typically found as a minor component of zinc ores in nature, was discovered in 1817 by both Karl Samuel Leberecht Hermann and Friedrich Stromeyer. They were examining impurities in a sample of the zinc carbonate mineral calamine (also known as cadmia in Latin), which subsequently led to the derivation of the element's name.
Following its discovery, cadmium found a range of applications. The first significant use of cadmium was in red, orange, and yellow pigments based on cadmium sulfides and selenides, which began on a small scale as early as the 1840s. Cadmium pigments, valued for their vividness and permanence, were one of the few options for stable pigments in this color range at the time of their introduction. As the industrial-scale production of cadmium metal commenced in the early twentieth century, cadmium pigments gained popularity, and other applications followed. Cadmium, being resistant to corrosion, can be deposited by an electroplating process to serve as a protective coating on metals such as steel that are more prone to corrosion. Nickel-cadmium (NiCd) batteries, first invented in 1899, became commonly produced starting in the mid-1940s and were the primary rechargeable batteries available for consumer electronics for the next fifty years. Cadmium can also be a component of silver-based solder alloys that are versatile and have high strength along with a uniquely low melting point, and cadmium compounds can be used to stabilize PVC plastics, significantly increasing their resistance to heat and general wear.
However, the use of cadmium for all these applications had one major downside: cadmium and many of its compounds are extremely toxic. Exposure to the metal's fumes or cadmium-laden dust often results in acute poisoning, causing severe flu-like symptoms, respiratory problems, and damage to the liver and kidneys within hours. Acute organ damage can also result from ingestion of large amounts of cadmium compounds, but long-term low-level exposure can lead to insidious damage, resulting in progressive kidney disease, gout, and dangerously weak bones leading to severe pain and fractures. Cadmium in industrial waste, landfills, and mines easily leaches into groundwater, from where it can be consumed in drinking water or accumulate in crops. All plants can absorb some cadmium from the soil, but some are particularly prone to concentrating the metal, which sometimes leads to tragic mass poisonings.
Concerns about cadmium's toxicity have led to workplace safety regulations, battery recycling programs, and a substantial decline in traditional uses of the metal. Alternative pigments such as cerium sulphide and azo pigments are now available for many applications, although some fine artist's paints still include cadmium. In most applications of corrosion-resistant thin films, zinc or aluminum plating can serve the same purpose as cadmium. Few solder formulas still include cadmium, and alternative stabilizers have been developed for the manufacture of PVC products. Finally, nickel metal hydride (NiMH) and lithium-ion batteries are now becoming economically viable and functionally comparable alternatives to Ni-Cd for rechargeable batteries in consumer electronics, although Ni-Cd batteries still have advantages to recommend them for some specialized applications.
A relatively new application for cadmium in compound semiconductors is becoming increasingly relevant. Cadmium can form II-VI class semiconducting compounds with selenium, tellurium, and sulfur, and can also be a component of several ternary semiconductors. The largest current use of cadmium semiconductors is in cadmium telluride thin-film photovoltaics, but they are also used in radiation detectors, electro-optic modulators, optical windows and lenses, photoresistors, and lasers. Additionally, ongoing research into nanoscale cadmium semiconductor crystals such as cadmium selenide quantum dots has shown promise for a variety of applications, including higher-efficiency LED-type lighting.
Cadmium is relatively rare and there are no common cadmium ores, so today the element is still obtained commercially as a byproduct of zinc mining. Cadmium sulfide is the compound most commonly found in zinc ores, and as it is easy to isolate and purify, it is the primary source of cadmium for industrial applications.
Cadmium: Cadmium is mainly obtained as a byproduct of mining and processing zinc, lead, and copper ores. It's also found in the minerals greenockite and otavite.
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52. Mercury - About Mercury: Mercury, the only metal that remains liquid at standard temperature and pressure, owes this unique property to an electron configuration that results in unusually weak metallic bonds. Its chemical symbol, Hg, is derived from the Latin term "hydragyrum," which translates to "liquid-silver." The element's common name, Mercury, is borrowed from the Roman god of the same name. Known to ancient civilizations, mercury's metallic nature was not initially understood, but its unique properties often led it to be viewed as special or even magical. Its earliest applications were ceremonial, decorative, or medical; it was used in medical ointments and elixirs, cosmetics, and reflecting pools, and was frequently buried in large quantities alongside deceased rulers. Some traditional healing practices still recommend the consumption of the mercury ore cinnabar for specific ailments or as a supplement for general health.
The dangers of acute inhalation of mercury have long been recognized, but it is now understood that the slow elimination of most forms of mercury from the body ensures that even low levels can cause severe damage if chronic exposure allows for significant accumulation. A famous example of such gradual poisonings resulted from the use of mercuric nitrate in processing the animal skins used in 18th and 19th-century hatmaking, which led to the coining of the phrase "mad as a hatter." Increasing recognition of the dangers of chronic mercury exposure and of widespread environmental contamination due to mercury-containing products has driven significant reduction in many classical uses of the element.
Perhaps the most longstanding use of mercury not based primarily on its alluring physical properties was in amalgamation. Mercury will form amalgams with most common metals with the notable exception of iron; as early as 500 BCE this was exploited for extraction or refining of silver and gold. This practice continued in precious metal mining for centuries, though its use dwindled with increasing recognition of mercury's toxicity until ceasing altogether in modern times. Amalgams were also widely used in dental fillings, and are still sometimes used this way today, though both toxicity and cosmetic concerns have led to their increasing replacement by alternative materials.
The pattern of widespread exploitation of unique properties followed by drastic scalebacks or total cessation of use in a given application due to greater recognition of safety risks has repeated throughout mercury's history. Liquid mercury is opaque, dense, and displays almost-linear thermal expansion, making it ideal for use in instruments for measuring temperature or pressure. It is still used this way in some industrial and technical applications, but has been largely removed from medical equipment and most consumer versions of such products. Additionally, as a liquid that conducts electricity, it was used in mercury switches, which were often used in home light switches and thermostats, but these uses were discontinued. Mercury was also a common component of some types of batteries, but concerns about contaminations of landfills have all but eliminated this use. Mercury sulfide, which occurs naturally as the mineral cinnabar, has been used to produce brilliant warm-colored pigments, most famously "China red", for centuries and is still used by some artists, but has been replaced by less-toxic pigments for most uses.
Even mercury's toxicity has been exploited for practical applications. Mercury has been used in insecticides, herbicides, wood preservatives, and anti-fouling paints, but widespread use of all of these products have been discontinued. The organomercury preservative thiomersal was once used widely in vaccines, and though unlike most mercury compounds it produced a metabolite-ethylmercury-that was known to be eliminated from the body relatively quickly and therefore be nontoxic at the extremely low concentrations used in vaccines, public concern about the potential for toxicity has led to its elimination from most formulations. Mercury has also been used as an antiseptic and a diuretic, but these uses are now exceedingly rare and continue to decline.
Reductions in mercury usage in industrial applications have proceeded somewhat more slowly than the elimination of mercury from consumer products. Traditional chloralkali plants use mercury as one electrode in the electrolysis of sodium chloride to produce sodium hydroxide and chlorine gas. New chloralkali plants are required to be designed for use of alternative technology that does not require mercury, but existing plants still consume the majority of mercury produced. Mercury also continues to be used in a number of niche laboratory applications, including liquid mirror telescopes, and in the production of a few compound semiconductor materials used for infrared detection.
A notable exception to the elimination of mercury from consumer products is seen in the proliferation of fluorescent light bulbs which contain small amounts of mercury vapor. The energy efficiency of fluorescent bulbs compared to traditional incandescent lighting is generally considered to be an advantage large enough to outweigh the risks associated with the small amount of mercury the bulbs contain, however such bulbs do require careful disposal, and other energy efficient lighting technologies such as LEDs are beginning to be a competitive alternative for at least some lighting applications.
Mercury occurs naturally in elemental form on occasion, but is mostly found as the sulfide mineral cinnabar. It is extracted from this mineral by roasting to produce mercury vapor and sulfur dioxide. Mercury is also sometimes recovered as a byproduct of silver and gold mining, and recycling of old mercury-containing devices is a significant source of the metal.
Mercury: Mercury is found in the minerals cinnabar, livingstonite, and corderoite. It's also present in raw materials such as coal, crude oil, and other fossil fuels.
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53. Copernicium - About Copernicium: Copernicium, previously known as ununbium, is a highly radioactive element that was first synthesized in 1996 by a German scientific team consisting of Sigurd Hofmann, Peter Armbruster, and Gottfried Munzenberg at the GSI Helmholtz Centre for Heavy Ion Research. The initial experiment yielded only a single atom of the element, and it took several years of additional work by the GSI team before the International Union of Pure and Applied Chemistry (IUPAC) recognized their claim of discovery in 2009. To date, only a handful of Copernicium atoms have ever been produced, which severely restricts our understanding of its properties. However, it is known that this Group 12 metal likely shares some characteristics with other Group 12 elements such as zinc, cadmium, and mercury.
In 2009, the GSI proposed the name Copernicium in honor of Nicolaus Copernicus, the renowned scientist who revolutionized our understanding of the world. After a standard period of discussion, the scientific community accepted the name, and it officially became Copernicium in February 2010.
Copernicium: Copernicium is a synthetic element that is not found naturally. It is produced by bombarding lead with zinc.
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54. Boron - About Boron: Boron, the only non-metallic member of the periodic table family that includes aluminum, gallium, and indium, is a metalloid or semimetal. It can mimic the behavior of either a metal or a nonmetal, depending on the reaction involved. Unique among nonmetals, boron has three electrons in its outer shell available for bonding. It is a strong electron-pair acceptor (a potent Lewis acid) with a high affinity for oxygen and is one of the few elements, along with carbon and nitrogen, known to form stable compounds with triple bonds.
Like its neighbor carbon, boron has multiple allotropes, or structural forms, all of which are extremely hard. Crystalline boron is a brittle, lustrous solid that ranges in appearance from jet black to silvery gray and is a poor electrical conductor. Another crystalline form is red, and amorphous boron is a dark brown powder with a lower density than the crystalline forms. Boron, like carbon, can form covalently bonded networks of molecules, and these two are the only elements that form multiple hydride compounds.
The name boron originates from the Persian or Arabic terms for the mineral borax (burah or buraq, respectively). Borax and boric acid have been known since ancient times in Europe, Tibet, and China, and were used by craftsmen to lower the melting point of other materials used in glassmaking and other applications. The first written reference to boron-containing compounds was by the 9th-century Persian alchemist Rhazes, who classified one of six groups of minerals as "boraces." The element was first isolated in 1808 independently by English chemist Sir Humphry Davy and French chemists Joseph-Louis Gay-Lussac and Louis-Jacque Thenard. Later, Henry Moisson isolated a purer sample by reducing boron trioxide with magnesium, a method that still bears his name.
The primary commercial application for boron is the use of borax (sodium tetraborate decahydrate, Na2B4O7• 10H2O) in soaps and household detergents, water-softening compounds to remove alkaline-earth ions like calcium and magnesium from water, adhesives, cosmetics, fire retardants, and glazes. It is also used to disinfect fruit and lumber, and plays a role in the manufacturing of paper, leather, and plastics. Sodium borate is used to manufacture borosilicate glass, a high-strength glass that is resistant to heat, chemical attack, and thermal shock. Applications for borosilicate glasses include bakeware, laboratory containers, and high-quality optical glass, as well as precursor materials for glass fiber insulation and textile glass fibers. Boron-containing glasses are generally preferred for flat display panel glass, as in LCDs, as these glasses have superior electrical and strength characteristics compared to other glasses available for these applications.
Boron is also used in several alloy products, including neodymium iron boron (NdFeB) magnets, which are the strongest magnets available and are found in microphones, magnetic switches, speakers, particle accelerators, and dozens of other electronic applications. Boron is also an important dopant molecule used in the production of semiconductor crystals. Several boron compounds are also important in electronics, including the neutron-detecting scintillator material cadmium borate, and boron subphtalocyanines, organoboron dye molecules with optical properties that are useful in organic LEDs and photovoltaics. Some other organoboron compounds have medical uses, either as treatment agents or as diagnostic markers.
Although not technically a metal, boron is playing an increasingly important role in advanced materials science, partly due to the unique properties of hexagonal boron nitride (hBN), a semiconducting material capable of forming two-dimensional sheets similar to carbon-based graphene. Boron nitride and boron carbide are both superhard materials and are widely used in cutting tools and as abrasives. Boron carbide is also a strong, heat-resistant material with a high strength-to-weight ratio, making it useful for armor and bulletproof vests. Additionally, boron carbide can absorb neutrons without forming dangerous long-lived radioactive waste, making it an important material in nuclear power plants. Several other engineered advanced materials also contain boron. These include borane derivatives, of interest for a variety of specialized applications including hydrogen storage, and lithium borosilicide, a key component of lithium-ion batteries.
Boron is a relatively scarce element in the universe, produced only via cosmic ray spallation rather than in the cores of stars. Despite composing merely 0.0003% of the earth's crust by mass, boron is very susceptible to fractionation in the earth's crust and therefore tends to be concentrated in deposits of an extensive array of borate (boron oxide)-containing minerals such as borax and kernite (its most common sources), colemanite, and ulexite. It is also present in meteorites, seawater, as a trace element in soils, and silicate minerals like tourmaline and datolite. Methods of obtaining boron include heating the oxide with powdered magnesium or aluminum, or passing an electric current through molten boron trichloride. The city of Boron in California, United States was named after the element and is home to the U.S. Borax Boron Mine, the world's largest borax mine. The other major source of the element is deposits in Turkey, although the element also is known to accumulate in areas of thermal and volcanic activity.
Boron: Boron is not typically found in its elemental form in nature. It's often found in compounds such as borax and boric acid.
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55. Aluminum - About Aluminum: Aluminum, a base metal recognized in 1808 by Humphry Davy, was initially named "alumium," which was eventually modified to "aluminum." The metal was first purified by another chemist in 1825. However, the extraction of the metal from ore was initially very challenging, making pure aluminum very valuable for some years. In the late 1880's, the Hall-Heroult process for extracting aluminum from minerals was developed independently by two chemists, making extraction much more economical and bringing the metal into more general use.
As the third most abundant element in the earth's crust and the most abundant metal, aluminum and its compounds have practically countless applications. The elemental metal is durable, lightweight, ductile, and malleable, making it easy to form using a variety of metalworking techniques. However, pure aluminum is soft and lacking in strength, so alloys of aluminum with other metals are generally used for most applications. Aluminum alloys are generally less dense than alternative metals of similar strength, making them particularly useful in applications where a strong but lightweight structure is needed. These alloys are used in the construction of vehicles and buildings, and are frequently the casing material for small electronics. Additionally, aluminum is a component of the magnetic alloys MKM steel and Alnico, which are both used to produce permanent magnets for a variety of uses. Aluminum is also a good thermal and electrical conductor, leading it to find uses as heatsinks and wiring in electronics.
Aluminum oxide, often called alumina, is one of the most common aluminum compounds. Its crystalline form occurs naturally as corundum, high-quality forms of which are used as gemstones and considered either rubies or sapphires depending on the colors imparted by trace impurities. These gems are the hardest natural substances after diamond, and are therefore extremely resistant to scratching. Synthetic versions are used in optical devices such as spectroscopes and lasers, shatter resistant windows, and as insulating substrates for silicon integrated circuits. Powdered forms of aluminum oxide are used as filler in plastics, as it is both white and fairly chemically inert. The same properties lead to its use in sunscreens and cosmetic products. The powder is also used as an abrasive in industrial and commercial applications from sandpaper to toothpaste, and as a catalyst or catalyst support for some industrial chemical processes. Alumina may be used in the production of zirconia aluminia, an extremely strong and corrosion resistant class of composite ceramics that are used in cutting tools and medical implants. Finally, alumina fibers are components of many experimental and a few commercial fiber composite materials, and alumina nanofibers specifically have attracted a great deal of research interest.
Aluminum silicates are also aluminum compounds of considerable commercial importance. A number of aluminosilicates occur naturally, often as microporous minerals known as zeolites or hydrated clay minerals such as kaolin. Natural zeolites can be used industrially, but most applications use synthetic zeolites. Zeolites are notable for their very regular pore sizes, which allow them to act as molecular sieves, separating mixtures based on particle size.This property is exploited for applications in water purification, research chemistry, and the precise separation of gases from mixed gas streams. Additionally, the mineral's porous nature allows it to filter select ions from nuclear waste, which can then be trapped permanently by pressing the mineral into a non-porous durable ceramic. Zeolites can also efficiently store heat, and are therefore used in heating, refrigeration, and energy storage applications. The high surface area provided by the porous material makes zeolites an excellent catalyst support material. Additionally, zeolites are used in laundry detergent, concrete and cement, medical applications, agriculture, and in aquarium filters and cat litter. Aluminosilicates are also frequently used to produce ceramics; notably, kaolin clay is the base material for the well-known ceramic porcelain.
There are many other notable aluminum compounds. Aluminum sulfates and alums are used in water treatment, paper manufacturing, fabric dying, fireproofing, and leather tanning. Aluminum chloride is used as a catalyst in oil refining and the production of synthetic rubber and polymers, while aluminum chlorohydrate is used in antiperspirants and in water treatment applications. Aluminum is a component of the semiconductor aluminum gallium arsenide, which is often used alongside gallium arsenide in semiconductor devices, and of antimony-aluminum phase change material used in phase-change memory devices. Lanthanum aluminate is a pervoskite ceramic that is of interest for use as a substrate for the growth of superconducting thin-films, and as a gate dielectric for use in next-generation metal oxide semiconductor field-effect transistors (MOSFETs).
Aluminum has a strong affinity for oxygen and is therefore rarely found in its pure state in nature. It is instead found primarily as oxides and silicates, and the primary commercial ore of aluminum is a mix of minerals known as bauxite. The Hall-Heroult process developed in the 19th century is still used today for the processing of aluminum ore. The process requires a significant amount of energy input, but all proposed alternatives have either been less viable economically or were ruled out due to environmental concerns. Since aluminum can be recycled for a fraction of the energy cost of removing new aluminum from ore, aluminum recycling is cost effective and practiced widely. The "secondary" aluminum produced from recycling therefore accounts for a sizable percentage of the aluminum used each year. Additionally, a number of aluminum-containing minerals are mined for direct use or use as compounds, rather than for extraction of metallic aluminum.
Aluminum: Aluminum is primarily obtained from the ore bauxite. It's also found in minerals such as cryolite, gibbsite, and boehmite.
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56. Gallium - About Gallium: Gallium, a unique element predicted by Dmitri Mendeleev in his 1871 periodic table as element 31 and tentatively named eka-aluminum, was discovered in a sphalerite sample by Paul Emile Lecoq de Boisbaudran through spectroscopic evidence. Lecoq, who later discovered more elements, named his first discovery gallium, derived from the Latin for Gaul, his native France's geographical area. For the next eighty-five years, gallium was primarily a curiosity-a metal that remains solid around room temperature but melts when held in the hand. However, it found some use in the preparation of metal alloys with special properties such as low-melting points, in high-temperature thermometers, and as the reflective compound in mirrors.
The usage of gallium underwent a significant transformation in the 1960s when gallium arsenide was developed as a semiconductor. This semiconductor exhibited different electrical properties than the more common silicon and was more suited to certain applications. Notably, gallium arsenide is a direct band gap semiconductor, meaning it can efficiently absorb and emit light. This property makes it useful in LEDs and lasers. Moreover, extremely thin layers of gallium arsenide can effectively absorb all photons from incident sunlight, unlike the thick layers of silicon required for the same task. This property allows for the creation of a type of thin-film solar cell. Gallium arsenide semiconductor devices also exhibit less noise than those produced from silicon, making them favored in many telecommunications applications.
In addition to being a component of gallium arsenide, gallium can be used to create several other semiconducting compounds. These gallium semiconductors find use in many applications, including light-emitting devices such as LEDs and lasers, photovoltaic and thermophotovoltaic cells, and integrated circuits. Gallium also finds use in a few highly specialized technical applications, including in neutrino-detecting telescopes, notable for the sheer volume of gallium they can require-the Gallium-Germanium Neutrino Telescope used by the SAGE experiment at the Baksan Neutrino Observatory in Russia used at least 55 tons of the liquid metal. It can also serve as a liquid metal ion source for focused ion devices. Gadolinium gallium garnets are used to fabricate optical components and as a substrate material for magneto-optical films and high-temperature superconductors. Finally, gallium phosphate is a piezoelectric material that can function at high temperatures unlike alternatives such as quartz, which makes it useful for pressure and force sensors in high-temperature applications.
While gallium is not a compound naturally involved in human biology, it is generally considered non-toxic at low doses and mimics some of the properties of iron in the body, making it useful in some medical applications. Gallium tends to concentrate in areas of high levels of inflammation and cell growth, and therefore radioactive isotopes of the element are used in scans for tracking the spread of some cancers and disorders of the immune system. Additionally, gallium salts are used to treat hypercalcemia that results from cancers metastasizing to the bones, and are under investigation as treatment for certain types of cancers. Gallium compounds are also known to be toxic to some disease-causing microorganisms, and organometallic gallium compounds have shown some promise as potential malaria treatments.
The few minerals which contain substantial percentages of gallium are too rare to serve as a commercially viable source of the element. Gallium is found in small amounts in the aluminum ore bauxite and the zinc ore sphalerite, and is therefore extracted from waste materials from the processing of these metals.
Gallium: Gallium is typically obtained as a byproduct of mining and processing bauxite and zinc ores. It's also found in trace amounts in the minerals diaspore, sphalerite, and germanite.
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57. Indium - About Indium: Indium, a unique element, was discovered in 1863 by chemists Ferdinand Reich and Hieronymous Theodor Richter while they were spectroscopically examining various ores in search of the element thallium. Instead of thallium's characteristic green emission lines, they observed a bright blue spectral line, which was not associated with any known element. They correctly inferred that their samples contained a new element, which they named indium, inspired by the indigo color of its spectral line. The following year, Richter succeeded in isolating pure indium metal.
For the first seventy years post-discovery, indium was primarily a curiosity. It was presented at the World Fair in 1867, but it wasn't until the late 1920s that major indium mining operations were established. This was driven by chemists interested in using indium as a hardening surface treatment for ferrous metals. The first large-scale application for the metal was as a coating for bearings in high-performance aircraft engines. However, it wasn't until 1952, when indium began to be used in semiconductor technologies, that demand for the metal increased.
Since 1992, the majority of demand for indium has been for a single semiconducting compound: indium tin oxide (ITO). When applied as a thin film, ITO forms an optically transparent conductive coating, making it ideal as a transparent electrode in electronic devices such as liquid crystal displays (LCDs), plasma screens, and touchscreen devices. ITO is also used in organic LEDs, solar cells, sodium vapor lamps, antistatic coatings, thin-film strain gauges, and electromagnetic interference shielding.
In addition to ITO, several other indium-based semiconductors have important applications. These semiconductors, including indium arsenide, indium phosphide, indium nitride, indium antimonide, and many alloys of these with other semiconducting compounds, are notable for their high electron mobility. They are therefore found in high-frequency electronics such as high-frequency transistors. These materials generally have direct bandgaps, making them suitable for optoelectronic devices such as LEDs, lasers, thin-film solar cells, radiation detectors, and integrated optical circuits.
Outside of semiconductors, indium is primarily used as a metal, either alone or in alloys, usually in applications that exploit its low melting point. Indium can be used to produce alloys such as Galistan, which are liquid at room temperature and can replace mercury in applications such as thermometers. Indium alloys are frequently used in seals found in low-temperature applications, as they maintain malleability and ductility at low temperatures. Indium-containing solders have become more important due to increasingly stringent restrictions on the use of lead, another low-melting-point metal once found in most low-temperature solders.
Two niche uses of indium are also notable. A radioisotope of indium is used in indium leukocyte imaging, which is used to track white blood cells in the body in order to identify sites of infection. Indium is also a component of control rods used in nuclear reactors, where it absorbs excess neutrons along with silver and cadmium.
Indium is not particularly rare-it is approximately as abundant as mercury-but there are no economically significant indium ore minerals. The metal must therefore be extracted from other metal ores where it occurs in trace amounts, and today is most commonly extracted from byproducts of zinc mining. Increasingly, indium is recovered from waste material produced by the ITO sputtering process, and even directly from scrap LCD panels. These recycling efforts vary in economic feasibility depending on the efficiency of the process and current prices of the metal, and therefore their use varies widely between countries and from year to year. Concerns about depleting world indium resources have led to substantial interest in developing alternative transparent electrode materials to substitute for ITO in electronics.
Indium: Indium is mainly obtained as a byproduct of zinc processing. It's also found in the minerals sphalerite, roquesite, and indite.
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58. Thallium - About Thallium: Thallium, the heaviest member of Group 13 on the periodic table, is a post-transition "poor metal" that is extremely malleable and has a low melting point. It is soft enough to be cut with a knife. Pure thallium is initially lustrous and silvery-gray, but it forms a dull bluish-gray film of thallium(I) oxide on its surface upon exposure to air. Prolonged exposure converts the film to a dark brown crust of thallium(III) oxide. When submerged in water, the oxide film disappears, and the metal regains its original sheen. Thallium metal is highly reactive with oxygen and acids and dissolves in nitric acid. French chemist Jean-Baptiste Dumas once referred to it as the "platypus of metals" due to its similarity to several widely varying elements: lead, silver, potassium, mercury, among others.
The discovery of thallium is credited to English chemist Sir William Crookes, although there is some debate over this. Crookes discovered the element in 1861 while attempting to isolate tellurium. He observed unfamiliar brilliant green lines in the emission spectrum after burning the sample. This method, known as flame spectroscopy, had been invented several years earlier by chemists Robert Bunsen and Gustav Kirchhoff and used to discover several elements. Crookes named his new element thallium after thallos, Greek for "green twig" or "shoot". Around the same time, French chemist Claude-Auguste Lamy had identified the element independently and isolated it one year later.
Thallium is quite scarce in the earth's crust, at about 0.7 mg/kg, roughly as common as iodine or tungsten. Thallium is not found free in nature, but rather is present in small amounts in ores of iron, copper, heavy-metal sulfides, and in polymetallic rock deposits on the ocean floor. Commercially, the element is obtained as a gaseous byproduct of lead and zinc refining, or in the process of obtaining sulfuric acid from pyrites.
Applications for thallium are mostly limited to the fields of electronics, medicine, and infrared optics. Despite its toxicity and potential carcinogenicity, the radioactive isotope thallium-201 is frequently used in medicine in scintigraphy-type stress tests to diagnose clogged arteries and heart disease. Thallium iodide in combination with iodides of indium, sodium, scandium, dysprosium, and occasionally tin, are used to produce the high-efficiency white light of metal halide lamps.
Thallium has multiple uses in the field of advanced optoelectronics including infrared optics, phosphors, and specialty glasses. The high refractive index of the optical crystals thallium bromoiodide (KRS-5) and thallium bromochloride (KRS-6) make them ideal materials for attenuated total reflection prisms, lenses, and windows in infrared spectrometers.
Thallium compounds have other special properties that give them unique uses. A eutectic thallium-mercury alloy with 8.5% thallium exhibits a melting point 20 degrees below that of pure mercury, making it applicable in low-temperature thermometers. Thallium is the only known impurity that causes lead telluride (PbTe) to exhibit superconductivity; the resulting thallium-substituted lead telluride, PbTe:Tl, is a semiconductor and thermoelectric material. Other superconducting materials like thallium barium calcium copper oxides (TBCCO) and various thallium cuprates exhibit T c as high as 127 K.
Thallium: Thallium is found in the minerals crooksite, lorandite, and hutchinsonite. It's also obtained from the iron pyrite and is found in manganese nodules on the ocean floor.
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59. Nihonium - About Nihonium: Nihonium (Nh), previously known as Ununtrium (Uut), is a transactinide element that belongs to the p-block of the periodic table and carries the atomic number 113. The initial claim for the synthesis of Ununtrium was made in 2003 by a collaborative team from the Joint Institute for Nuclear Research in Dubna, Russia, and the Lawrence Livermore National Laboratory in Livermore, California, USA.
However, the formal recognition for the discovery of the element was given by the International Union of Pure and Applied Chemistry (IUPAC) in 2015 to a team at the RIKEN institute in Japan, led by Kosuke Morita. This marked the first official discovery of an element in Asia. The superheavy element was synthesized by the RIKEN team by bombarding a target of curium with sodium ions, initiating a chain of decay reactions starting with 266Bh.
In honor of the Japanese version of their country's name, the RIKEN physicists named the new element Nihonium, symbolized as Nh. After a review period of six months, the name was made permanent in December 2016. This marked a significant milestone in the field of chemistry, highlighting the global contributions to the expansion of the periodic table.
Nihonium: Nihonium is a synthetic element that is not found naturally. It is produced by bombarding atoms of americium with ions of calcium.
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60. Carbon - About Carbon: Carbon, while not the most abundant element in the universe, holds a significant place on Earth. Constituting only 0.5% of the universe, it is surpassed by hydrogen, helium, and oxygen. Yet, carbon forms the foundation of life as we know it and is pivotal to both biological and environmental processes. Moreover, it underpins all technology used by society, from energy for transportation to industrial manufacturing. Its role is increasingly prominent in advanced high technology sectors such as semiconductors, electronics, nanotechnology, and green technology.
The versatility of carbon is reflected in its diverse forms. Elemental carbon, often classified as a nonmetal (though sometimes considered a semimetal or metalloid), exists in several structural forms or allotropes. These allotropes, which include graphite and diamond, vary widely in appearance and properties. The set of known allotropes has expanded with the discovery or artificial synthesis of additional forms using advanced technology such as chemical vapor deposition.
Elemental Forms Graphite, an opaque black form of carbon, possesses a layered hexagonal crystal structure in its alpha form. It is extremely soft, thermodynamically stable, and electrically conductive. Graphite occurs naturally in various rocks and minerals worldwide, but it can also be artificially synthesized by subjecting silicon carbide (or carborundum) to high temperatures to vaporize the silicon, leaving behind graphitized carbon. Its softness makes it an excellent lubricant in powdered form and a common component in items such as heat shields, nuclear reactor components, and melting crucibles for high-temperature processes like metallurgy and crystal growth.
Pyrolytic graphite (PG) is a chemically inert, high purity form of graphite artificially synthesized via chemical vapor deposition. It is extremely anisotropic, exhibiting both directional electrical and thermal conductivity, and extremely heat resistant. It is typically commercially employed in coatings and heat spreaders for electronics components.
Black carbon, also known as soot or coal, was the earliest form recognized and utilized by humans. This form of carbon usually has a black appearance, and varying structures depending on the amount of heat and pressure that has been applied to the material.
Diamond, a transparent crystalline form of carbon, is the hardest known naturally occurring material on the planet. Though well known as a precious gemstone, diamond has technical applications such as in the precision cutting and grinding of optical glass and steel.
Amorphous carbon is a reactive form of carbon that lacks a defined crystal structure. Typically, amorphous carbon refers to coal and other carbide-derived carbons that are impure and neither graphite nor diamond.
Glassy carbon, or vitreous carbon, is a non-graphitizing carbon which combines ceramic and glassy characteristics with those of graphite. This gives glassy carbon many important properties, such as high temperature resistance, hardness, low density, low electrical resistance, low friction, low thermal resistance, extreme resistance to chemical attack and impermeability to gases and liquids.
Nanostructured Forms Graphene is a two-dimensional, single layer of carbon atoms in a hexagonal lattice. It is the basis of other discovered two-dimensional elemental forms such as hexagonal boron nitride, and the applications for these materials are numerous.
Carbon nanotubes are another allotrope of carbon with a cylindrical nanostructure. Nanotubes have a significantly larger length-to-diameter ratio than any other material, with ratios of up to 132,000,000:1 having been constructed.
Fullerenes, or buckeyballs, are molecules of carbon in the form of a hollow sphere, ellipsoid, tube, and a variety of other shapes. Fullerenes have a similar structure to graphite, which is made up of stacked graphene sheets in linked hexagonal rings.
Organometallics & Metalorganics Organometallic chemistry is the study of chemical compounds that have a minimum of one bond between a metal and a carbon atom of an organic compound. Organometallic chemistry incorporates characteristics of both inorganic and organic chemistry.
Compounds Carbonates are salts of carbonic acid that consist of one carbon atom surrounded by three oxygen atoms. This allows the oxygen atoms to link with other metal atoms in order to form compounds such as calcium carbonate and magnesium carbonate.
Carbides are very strong and heat-resistant materials used in industrial cutting, high melting crucibles, and furnace equipment. Carbides are composed of carbon and a less electronegative element with examples such as calcium carbide, silicon carbide, tungsten carbide, and iron carbide.
Alloys There are many carbon alloys, with the most common being steel. According to the American Iron and Steel Institute, the true name for steel is in fact carbon steel. Steel has many applications but the most important are within the construction, transportation, energy, packaging, and appliance industries.
Applications for Carbon Carbon has many applications throughout an immense number of industries. The most prominent of these is the fossil fuel industry, where hydrocarbons in methane gas and petroleum are used for fuel. Other valuable sources of carbon are in carbon-containing polymers that are produced in plants in the form of cotton, linen, and hemp. These carbon-containing polymers can also be procured from animals in the form of wool, cashmere, and silk. Carbon-containing polymers have obvious applications in the clothing industry.
A new application for carbon that is being developed is within battery anodes. Carbon-coated particles are used specifically in lithium-ion batteries, in which the carbon coating on the particles allows lithium ions to pass through freely, while limiting the movement of the particle within its shell. Carbon materials are also finding applications within the defense industry, with carbon nanotubes being substituted for copper wire and cables in aerospace and defense electronics due to its significantly lighter weight. Another carbon form that is finding new uses is carbon foam, which is applicable as a container for active materials with needs for thermal energy storage, electric energy storage, absorbents for large molecules and others including microwave absorption.
Carbon: It is chiefly obtained from graphite, which is mined in countries including China, Mozambique, Brazil, Madagascar, and India.
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61. Silicon - About Silicon: Silicon, while omnipresent, is rarely found as a free element in nature. It primarily occurs as silicon dioxide, better known as sand or quartz, or in silicate minerals, typically in the forms of clay or rock. Antoine Lavoisier first suggested in 1787 that silica sand was likely the oxide of a previously unknown element. In 1808, Sir Humphry Davy named this hypothetical element "silicium", combining the Latin silex, meaning stone, with the traditional -ium ending often given to metallic elements. The name was changed to silicon in 1817, as the -on ending suggested its closer relation to the non-metallic elements boron and carbon. However, it wasn't until 1823 that the Swedish chemist Jons Jacob Berzelius finally succeeded in preparing pure amorphous silicon and was given credit for "discovering" the element.
The majority of commercially used silicon is never separated from the materials in which it naturally occurs. These materials are often processed minimally before use. Silicate clays are used to produce whiteware ceramics such as porcelain and in the making of ceramic bricks and cement used as building materials. Silicate-containing rock such as granite is used directly in structural and decorative applications, and silica sand mixed with gravel and cement produces concrete. Sand is also used widely as an abrasive and as a filler in plastics, rubber, and paints. Additionally, diatomaceous earth, a form of silica rock consisting of fossilized remains of diatoms, has many direct commercial applications, especially as an absorbent, a filtration medium, a mild abrasive, and a natural pesticide.
More refined silicon products account for a much smaller portion of commercial silicon usage, but nonetheless are extremely important economically. Common silica sand is the starting point for the production of a variety of refined silica products, other silicon compounds, silicon-containing alloys, and elemental silicon at various levels of purity, all of which play significant roles in industry.
Silicon in Alloys Silicon is commonly used as an alloying element. Silica sand is reduced with carbon in the presence of iron to produce ferrosilicon, which can then be used in silicon-containing steels. In molten iron, silicon aids in maintaining carbon content within narrow limits required for a given steel grade. Used in larger amounts, as in electrical steel, silicon favorably influences resistivity and ferromagnetic properties of the material.
High-Strength Ceramics First produced synthetically in the nineteenth century, silicon nitride has been known to science for about as long as silicon carbide, but nonetheless took a much slower path to commercial exploitation. The potential of silicon nitride as a refractory material was first recognized in the 1950s, and in fact, the material came to be used as a binder in silicon carbide ceramics, a use which continues to some extent today.
Silica Glasses In common usage, glass refers to soda-lime glass, a silica-based glass produced by melting quartz sand along with sodium carbonate, lime, dolmite, and aluminum oxide. This is the glass commonly used in window panes and beverage containers. Most other products commonly known as glass are also silica-based, but have differing compositions intended to produce properties favorable for specific uses.
Synthetic Quartz Quartz is a natural piezoelectric material that finds use in crystal oscillators used to mark time in clocks and digital devices, and to standardize frequency in radio frequency devices. Quartz for this use is generally produced synthetically from silica sand, as this allows for precision engineering of crystal properties.
Silicones Silicones are mixed organic-inorganic polymers generally consisting of a silicon-oxygen backbone connected to hydrocarbon side groups. Varying the hydrocarbon groups present, silicon-oxygen chain lengths, and the degree of crosslinking can produce a wide range of materials, from silicone oil lubricants to hard silicone resins, but all tend to exhibit low thermal conductivity, chemical reactivity, and toxicity.
Ultra High Purity Silicon in Electronics and Photovoltaics Despite the fact that wafer silicon used in semiconductor devices accounts for only a tiny fraction of the commercial use of the element, this single application is the one most intimately tied to public conceptions of silicon, as its influence on modern life has been profound.
Synthetic Silica Products There are many forms of synthetic silicon oxide, including precipitated silica, colloidal silica, silica gel, fumed silica, and silica fume. Though each product is primarily silicon dioxide, each is produced as a result of a different industrial process, and they vary in particle size. Commonly, these products are employed as mild abrasive agents, anti-caking or thickening agents in food, absorbants, or as filler material in plastics, rubbers, silicones, or cement, though precise end uses vary by form.
Silicon: Silicon is chiefly obtained from quartz, which is not much more difficult to mine than scooping up sand. Silicon is also obtained from the minerals mica and talc.
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62. Germanium - About Germanium: Germanium, a semiconducting metalloid, was predicted by Mendeleev in his first Periodic Table of the Elements in 1869. He named it ekasilicon and accurately predicted its properties based on its position in the table. The actual element was discovered by Clemens Winkler in 1886 and named germanium after his native Germany.
Germanium's use in electronic devices predates that of silicon, the more famous element. The first transistors were made from germanium in Bell labs in 1947. However, the abundance of silicon and the technologies developed for its use led to silicon being used in many more semiconductor applications, including standard computer chips. For many years, germanium played a limited role in semiconductor devices. Today, new technologies are making germanium a key material for electronics applications again. Germanium is preferred over silicon in some types of photovoltaic cells used for solar energy harvesting and is used as a key substrate material in the production of high-brightness LEDs for various applications. Microchip designs using germanium-on-insulator or silicon-germanium technology are also seeing increased use.
Germanium and some of its compounds have favorable optical properties. Germanium oxide, for instance, has a high index of refraction and low optical dispersion, making it suitable for use in wide-angle lenses and some microscopes. Germanium glass is transparent to infrared radiation, making it useful in thermal imaging cameras, night vision systems, and sensitive infrared detectors. Germanium is also used in the material germanium-antimony-tellurium, or GeSbTe, a phase change material used in rewritable optical disks and other phase change memory devices.
In addition to its electronic and optical applications, germanium finds uses in other key areas. Germanium oxide is used as a catalyst in the making of many plastics. When added in small amounts to sterling silver, germanium reduces firescale and tarnish, and makes the final metal harder. Despite not having any proven medical function and being potentially hazardous if consumed, germanium is nonetheless found in some nutritional supplements.
Germanium is not particularly rare, but it is not found in any mineral in large enough percentages to be worth mining specifically for it. Instead, germanium is derived from concentrates produced as byproducts of mining for other metals, particularly zinc, and is also recovered from the fly ash of some coal power plants.
Germanium: Germanium is never found as a pure metal in nature, but trace amounts occur in many minerals, including common metallic ore minerals such as the zinc mineral sphalerite.
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63. Tin - About Tin: Tin, a non-toxic metal known since antiquity, can present itself in two forms: silvery and malleable or dull grey and brittle, depending on its crystalline structure. Its chemical symbol, Sn, is derived from the Latin term 'stannum'. Originally, 'stannum' referred to a mixture of silver and lead, but by the 4th century BCE, it came to denote tin. The English term "tin" has Germanic roots, but its exact origins remain unknown.
Tin played a pivotal role in human civilization as a key component of bronze, the first intentionally produced alloy. The uneven global distribution of tin ore deposits necessitated the development of trade networks, connecting distant tin sources to regions lacking in tin. Before the advent of bronze-making techniques, copper was widely used for decorative and functional purposes, but its softness limited its utility. Pure tin also did not possess ideal properties for metalworking. However, adding tin to copper produced an alloy that was more workable than tin and harder than copper, and also easier to melt and cast. This technological advancement enabled the production of stronger tools and weapons, marking the transition of societies into the "Bronze Age".
Even with the advent of the "Iron Age" and the subsequent rise of steel and aluminum as the most commonly used metals, copper-tin alloys have retained a significant place in industry. They are valued for their corrosion resistance, especially in marine environments, and their inability to produce sparks when struck against a hard surface. These properties make them ideal for use in ship propellers, submerged bearings, and tools used in flammable gas environments. Additionally, the alloy's notable acoustic properties and low metal-on-metal friction make it suitable for use in musical instruments like bells and cymbals, and in springs and bearings.
Tin has also been used in other alloys such as pewter, and in soft solders with lead or, more recently, silver and copper. It can be used in almost pure form for punched tin art and as a low-toxicity and corrosion-resistant plating for steel, as seen in tin cans. Commercial tin is almost never entirely pure, as intentionally added trace impurities are necessary to prevent "tin-pest", the conversion of metallic tin to brittle crystalline form at low temperatures. Molten tin is necessary for the process used in making most window glass, termed "float glass". Additionally, tin-nickel electrodes are used in some types of lithium-ion batteries.
Stanene, a novel material composed simply of tin atoms arranged in a single layer, exhibits the unique property of acting as a topological insulator, conducting electricity without energy loss like a superconductor, but only at the edges of the material. Materials that exhibit this property are of interest for use in next-generation integrated circuits enabling the production of smaller, faster, and more energy-efficient computers.
Several tin compounds also have important applications. Indium tin oxide is a conductor that can be applied by physical vapor deposition in a transparent film, and is used in liquid crystal displays, touch panels, organic light-emitting diodes, solar cells, and defrosting coatings for airplane windshields. Tin dioxide is a white powder used to opacify or impart white color to ceramic glazes, polish multiple types of hard surfaces, and as a protective coating on glass. Additionally, it may be used in detectors for carbon monoxide or other gases. Organotin compounds are important in industrial chemistry, where they are especially noteworthy for acting as PVC stabilizers less toxic than the cadmium-based alternatives, and in laboratory organic synthesis. These compounds may also be used as biocides or preservatives. Finally, niobium tin is a superconducting compound that can withstand higher temperatures and greater magnetic field strengths than comparable materials, and therefore finds use in superconducting materials.
Tin metal is produced mostly from its primary ore cassiterite. This tin oxide is reduced to tin metal in the presence of a carbon source, and subsequently purified as necessary for a given application. Increasingly, recycled scrap metal is also a notable source of tin.
Tin: The main source of tin is cassiterite (SnO2), a tin oxide mineral.
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64. Lead - About Lead: Lead, a soft and malleable metal with a low melting point, is easy to work with and cast. Its ease of extraction from its ore led to its early use by human societies. The earliest lead artifacts, discovered in present-day Turkey, date back to 6400 BCE. Lead was most extensively used in antiquity by the Romans, who industrially produced the metal as a byproduct of silver smelting and used it to manufacture water pipes. The Romans referred to the metal as 'plumbum', from which the element's symbol on the periodic table and the English word "plumbing" are derived. The English term "lead" has Anglo Saxon roots, but its precise etymology remains unclear.
Ancient civilizations were somewhat aware of lead's toxicity, as several Greek and Roman scholars noted ailments such as stomach pains and paralysis in workers who frequently handled the metal. Despite this, lead was used in a variety of applications, including pipes, dishes, cosmetics, coins, and paints, and even intentionally added to foods in the form of lead acetate. Over time, further evidence of the element's toxicity accumulated, but the severity of the risk still failed to be fully appreciated or adequately mitigated. After the fall of the Roman civilization, lead continued to be used in pipes and artist pigments, and lead oxide was used to make leaded glass or lead crystal. Lead glass containers were often used to store alcoholic beverages for long periods, allowing lead to leach into the liquid. Lead was also a major component of type metal, the alloy used to produce the movable type used in printing presses.
Lead compounds were ubiquitous well into the twentieth century: lead pigments were commonly found in artists' paints and house paint, tetraethyllead was used as an antiknock agent in automotive fuel, and lead solder was used to seal joints between pieces of pipe used to carry drinking water until new regulations were effected starting in the 1970s. The effects of these applications linger even today-leaded fuel is still sold in developing nations and for some types of aircraft, and lead in plumbing and paint in older buildings still often causes neurotoxicity in children, who are particularly susceptible to lead's health effects.
Today, lead continues to be used, though primarily in applications where the health and environmental risks are low, or where no suitable alternatives have yet been presented. More than half of all lead produced annually is used in lead-acid car batteries. Though using such toxic batteries is not ideal, alternatives are being researched and the majority of lead-acid batteries are recycled, keeping the majority of their lead content out of the waste stream. Lead is often used to line walls or storage containers to provide radiation shielding, and in weights used in sports equipment and applications such as scuba diving and boat ballast, all applications that present relatively low environmental risk. Lead oxide is still used to produce high-refractive index glass and to produce glass solder. These glasses are mostly used for optical applications or in electronics, and therefore the concern of lead leaching into liquids meant for consumption is not significant. Finally, lead-containing soft solder is being phased out of use in electronics due to concerns about leaching following the disposal of the devices.
One final use of lead is in semiconductor devices. There are four binary lead semiconductors: lead iodide, lead sulfide, lead selenide, and lead telluride. Each of these is used in producing radiation detectors-lead iodide in detectors of high-energy radiation such as x-rays or gamma rays, and the remaining three in infrared detectors. Additionally, nanocrystals or "quantum dots" of these compounds, in addition to ternary lead semiconductors, are areas of active research. There is potential for lead-containing quantum dots to be used in solar cells or advanced display screens in the future.
The most commonly exploited lead mineral is galena, a naturally occurring form of lead sulfide. Lead ores are roasted to produce lead oxides, which are then reduced to metallic lead. Only about half of lead used annually comes from newly mined ores; the rest is acquired through recycling.
Lead: Lead is chiefly obtained from the mineral galena (lead sulfide). Other common lead-bearing minerals include anglesite (lead sulfate), boulangerite, cerussite, (lead carbonate), minim and pyromorphite.
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65. Flerovium - About Flerovium: Flerovium, a superheavy transactinide element, was first synthesized in 1998 by the Joint Institute for Nuclear Research located in Dubna, Russia. A repeated synthesis in 1999 was required to confirm the discovery. The International Union of Pure and Applied Chemistry (IUPAC) officially recognized this discovery in 2011, following the successful production of several different isotopes of the element by both the UC Berkeley and the GSI nuclear laboratories in 2009. The element was named after the Flerov Laboratory of Nuclear Reactions, which was named in honor of Soviet physicist Georgy Flyorov. Flyorov's work and advice to the USSR government led to the development of the country's atomic bomb project. The name 'Flerovium' became official in 2012.
The most stable known isotope of flerovium has a half-life of a mere 2.6 seconds. However, it has been proposed that nuclear isomers of this isotope may possess longer half-lives. As relatively few atoms of flerovium have been synthesized, its chemical properties remain poorly understood and are a subject of ongoing investigation. Currently, there are no applications for flerovium outside of basic scientific research.
Flerovium: Flerovium is obtained by the fusion process of bombarding plutonium with calcium.
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66. Nitrogen - About Nitrogen: Nitrogen, the seventh most abundant element in our galaxy and constituting nearly eighty percent of Earth's atmosphere, is a vital component of life. It is a primary constituent of proteins and DNA, often determining the success of organism growth in various environments. Early agricultural practices, such as crop rotation and animal waste fertilization, were intuitively developed to maintain adequate soil nitrogen levels for plant growth.
Historically, nitrogen compounds were utilized by alchemists. Nitric acid, known as aqua fortis, was often prepared by treating niter (potassium nitrate) with sulfuric acid. Potassium nitrate, also known as saltpeter, was later used in explosive mixtures like gunpowder. Initially, potassium nitrate was derived from natural sources, often from human or animal waste. The production of saltpeter became so crucial that in many European countries, government agents could confiscate soils suitable for its production, and some even mandated the collection of human or animal waste for this purpose.
Nitrogen was also a component of aqua regia, a mixture of nitric and hydrochloric acids capable of dissolving nearly any metal, including gold. Historical texts often reference the use of sal ammoniac (ammonium chloride), another nitrogen compound, for this purpose. Sal ammoniac was collected from deposits near the Temple of Amun in ancient Libya, and its name, meaning "salt of Amun," serves as the basis for the modern names of all ammonium compounds. Ammonium chloride found use as a food additive, a flux in soldering tin, a medical treatment for various ailments, and in the preparation of other ammonium compounds.
Despite the widespread historical applications of nitrogen compounds, the element itself was discovered relatively late. In the mid-eighteenth century, chemists began to study common gaseous compounds. They recognized that air had components that would support life and components that would suffocate them. Dr. Joseph Black studied the first of these suffocating gases, "fixed air" or carbon dioxide. Shortly thereafter, Henry Cavendish showed in experiments that another component of air also did not support life but was chemically distinct from "fixed air". In 1772, Daniel Rutherford, Dr. Black's student, isolated this same substance and published his findings regarding the substance which he called "phlogisticated air". The famous chemist Antoine Lavoisier called this gas "azote" from the Greek azotos meaning "lifeless". This name was retained in some languages, and is the basis of the English names of some nitrogen compounds such as azides. The modern English name for the element comes from the association of the gas with nitric acid, which was known to be derived from niter.
Coincidentally, at this time, other scientists were beginning investigations into the chemistry of plant nutrition. Europe's population was booming, and concerns about this growth outpacing the capacity for food production, particularly as highlighted by Thomas Malthus's "Essay on Population, had helped produce an intense focus on increasing agricultural productivity. By the early nineteenth century, the importance of nitrogen content in fertilizer was recognized, and demand for fertilizers rich in nitrates began to boom. Relatively few large deposits of nitrate minerals exist, but one such source was found in South America: the salt flats of the Atacama Desert. By 1830, sodium nitrate was exported from South America to Europe for use as fertilizer, as was guano, a source of both nitrates and of phosphorus, another essential plant nutrient. Chemists also determined a way to convert the Atacaman nitrate salts into quality saltpeter for use in gunpowder and explosives, which further drove demand for this resource.
Though small initially, this trade grew rapidly, and soon grew contentious-in 1879, Bolivia, Peru, and Chile went to war for control of the Atacama desert and its associated saltpeter trade. Europe's intense and ever-increasing demand for saltpeter, in addition to its heavy reliance on South America for its supply, prompted increasingly urgent discussion of what came to be known as "The Nitrogen Problem". It was quickly recognized that atmospheric nitrogen was potential solution to this problem-a nearly limitless potential source of nitrates for fertilizer and explosives-but that it needed to be "fixed" into forms that could be used by plants. Thus, a race began to devise some chemical means of achieving nitrogen fixation.
This chemical quest was enormously difficult; in its pure form as a diatomic gas, nitrogen exhibits a profound chemical stability due to the strength of the triple bond uniting the two atoms, a configuration that requires enormous energy inputs to disturb. Early chemical processes inefficiently produced nitrous oxides using massive amounts of electricity, and were used industrially only briefly. The real breakthrough came from a German chemist named Fritz Haber, who developed a process that produced ammonia from hydrogen and nitrogen gases at high temperatures and pressures. Haber's initial process required expensive catalysts, but another chemist, Bosch, developed a more economically viable iron-based catalyst, and scaled up the process for industrial production. The Haber-Bosch process, as it came to be known, is still quite energy intensive, but was a major advance over alternatives and allowed chemically-fixed nitrogen fertilizers to come into widespread use. The use of these fertilizers is said to have saved millions from starvation, and Fritz Haber was awarded the 1918 Nobel Prize in Chemistry for his role in what has since been called the most important industrial process ever developed.
However, the plentiful fixed nitrogen derived from the Haber-Bosch process was not all used for fertilizer. It could also be easily used to produce saltpeter for gunpowder, as well as potent nitrogen-based explosives. Both nitroglycerine (the explosive component of dynamite) and trinitrotoluene (TNT) had both been initially synthesized in the mid-nineteenth century, but could now be manufactured and used in warfare at unprecedented rates. Nitrogen compounds have retained dominance in explosive applications into modern day: plastic explosives such as C-4 all require explosive nitrogen compounds. Beyond their obvious military utility, nitrogen explosives are also important in mining, and as propellants in devices such as automobile airbags. Unfortunately, the historic link between nitrogen fertilizers and the malicious use of explosives remains salient, as improvised explosives can be produced easily from common fertilizers such as ammonium nitrate. The significant threat imposed by nitrogen explosives has lead to strict regulation of many such nitrogen compounds.
Nitrogen finds many applications beyond the fields of agriculture and warfare. Nitrogen gas, purified from air through fractional distillation of liquid air, pressure swing adsorption, or membrane separation, is used widely in industry, serving as filler gas in food packaging, a working atmosphere in the manufacture of delicate electronics, and in dozens of other settings where a fairly inert environment is required. Liquid nitrogen is equally ubiquitous as a relatively inexpensive means to maintain temperatures far below the freezing point of water, which is used in many industrial processes, cryopreservation of biological tissues, and even in the production of novel food products in molecular gastronomy. Nitrous and nitric acids continue to be important reagents in analytical and industrial chemistry, and the simple nitrogen compound ammonia is important as a solvent and antiseptic frequently found in cleaning products, and in many niche applications.
Many additional classes of nitrogen compounds also have important uses. A nitrogen atom connected to a carbon atom with a triple bond is known as a cyano group, and both inorganic and organic compounds containing this group, known respectively as cyanides and nitriles, have important applications. Most cyanides are highly toxic due to the ability of the CN- ion to inhibit enzymes necessary for aerobic respiration, but they are nonetheless important for the cyanide process for mining gold, as well as in the industrial production of nitriles. Commercially useful nitrile compounds include cyanoacrylates, strong adhesives known under trade names such as Super Glue, and various polyacrylonitrile materials. The latter class includes nitrile rubber, used in non-latex disposable gloves, acrylic fiber, used in textiles and as a precursor to carbon fiber, and various copolymer plastics.
Nitrogen is in fact a key component of many important synthetic materials. Polyacrylamide materials absorb water, allowing them to act as water-soluble thickeners, flocculants and as soil conditioners that increase aeration and reduce water run-off. In gel form, they additionally are important in electrophoresis methods in biological research and in soft contact lenses. Celluloid, a nitrated cellulose polymer, was once used for standard photographic film, but its use was discontinued due to fires associated with its extreme flammability. Polyamides both occur naturally, as proteins, and as ubiquitous synthetic fibers such as kevlar and nylon, all of which owe their durability and strength of their amide linkages, which form from between carboxylic acids and nitrogen-containing amine groups. Finally, polymers called polyphosphazenes, which have backbones composed of phosphorus and nitrogen, are used in many specialty applications due to their durability and ability to be fabricated to produce useful properties such as fluorescence.
Synthetic nitrogen compounds, particularly small-molecule variants, play a crucial role in various industrial applications. Azo compounds, characterized by the R-N=N-R' functional group, are key constituents of dyes and pigments. Their applications range from textile dyeing and artist paints to industrial coloring agents. They are especially valued for their lower toxicity compared to metal-based pigments. Some azo compounds also find use in technical applications such as the recording layer of CD-R and DVD-R optical discs, sunlight-absorbing compounds in dye-sensitized solar cells, and pH indicators.
Moreover, many synthetic nitrogen compounds serve as biological agents, including pharmaceuticals and pesticides. Compounds such as amines, amides, and triazoles often mimic the structure of natural biological compounds to replicate or inhibit their functions. The highly stable cyano group is frequently added to drugs to prolong their half-lives in the body.
Hydrazine, a nitrogen compound derived from ammonia, is vital in synthesizing many of these small molecules and precursors to nitrogen polymers. It also serves as a significant aerospace fuel. Another notable ammonia derivative is nitrous oxide, known for its analgesic properties and use as 'laughing gas'. It is used as an oxidizer in rocket motors and combustion engines, and as an aerosol propellant.
Lastly, nitrides, which are simple compounds of nitrogen and a metallic or metalloid element, are commercially significant materials. Silicon and boron nitrides, extremely hard ceramics, are used as refractory materials, cutting materials, hard coatings, and components of composite materials. Silicon nitride finds additional use in orthopedic implants, durable and low-friction bearings, and as an insulator or etchant mask in integrated circuit manufacturing. Boron nitride, stable under extreme conditions, is useful as a lubricant and in nanomaterials for applications in chemical catalysis, computing devices, and aerospace applications. Lithium nitride, capable of storing large volumes of hydrogen gas, is being explored for use in hydrogen-based alternative energy solutions. Lastly, gallium nitride, a wide-bandgap semiconductor material, is crucial for producing light-emitting diodes (LEDs).
Nitrogen: Nitrogen is chiefly obtained by reacting air with hydrogen from natural gas to make ammonia.
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67. Phosphorus - About Phosphorus: Phosphorus, a nonmetallic element akin to nitrogen, is a paradoxical entity. It is a vital component of essential organic compounds like DNA, ATP, and phospholipids, underscoring its importance to life. Yet, it is also a part of dangerous explosives and potent poisons, such as organophosphate nerve agents. The dual nature of phosphorus is intertwined: its biochemical roles are enabled by the same chemical properties that make it highly reactive, while the deadly effects of nerve agents stem from their structural similarity to the natural targets of enzymes they irreversibly inhibit. This complex chemistry of phosphorus makes it versatile, defying simplistic characterizations.
Phosphorus, despite its omnipresence, was unknown as an element for much of human history due to its high reactivity preventing its natural occurrence outside compounds. Hennig Brand first isolated elemental phosphorus in 1669 while experimenting with urine in an attempt to create the philosopher's stone. Instead, he discovered a mysterious white substance that glowed in the dark, a phenomenon now understood to be a slow light-producing reaction with oxygen. Brand's discovery was eventually sold to D Krafft, who showcased the substance across Europe. The revelation that the substance was derived from urine led to its production by numerous other chemists.
The first commercial application of phosphorus was in matches. However, the early match industry was plagued with issues. White phosphorus, the form Brand isolated, was both highly unstable and toxic, leading to accidental fires and worker poisonings. In 1850, Anton Schrotter von Kristelli demonstrated that controlled heating could transform white phosphorus into a more stable, non-toxic red substance. Today, we know that elemental phosphorus can also form even more stable violet and black crystalline forms under temperature or pressure, although the red and white forms remain the most commonly used. The use of red phosphorus and various safety-enhancing design elements in "safety matches" enabled the widespread production and use of significantly safer phosphorus matches.
In 1769, Johan Gottlieb Gahn and Carl Wilhelm Scheele discovered that bones contained calcium phosphate and that the pure element could be extracted from bone ash. For the next seventy years, bone remained the primary source of the element. By the 1840s, bat and bird guano were recognized as another important source of phosphates, especially for use in fertilizers. Phosphate rock was also used as a phosphorus source as early as 1850, but this production method did not become significant until after the development of the electric arc furnace in 1890, which made the process considerably more feasible.
The industrial extraction of phosphorus from phosphate rock did not reach the scale of today's phosphorus industry until the World Wars, during which white phosphorus was widely used in weapons. Phosphorus is used in many incendiary devices, such as incendiary bombs and Molotov cocktails, as well as in smoke screens. Phosphorus burns vigorously, producing difficult-to-extinguish fires and horrific wounds when it contacts human skin. Interestingly, its use is still permitted for bombs and smoke-producing munitions, but it is classified as a chemical agent when used in direct bombardment, and therefore this use is prohibited. The organophosphates developed for warfare are also considered illegal chemical weapons, though many countries still retain stockpiles of these compounds, which include VX and sarin gas. However, organophosphate pesticides, which operate through the exact same mechanism as these chemical weapons-the inhibition of acetylcholinesterase, which is necessary for normal nerve function-- and can be lethal in small doses when inhaled, ingested, or even absorbed through the skin, remain common tools in commercial agriculture. The potency of these compounds, as well as their extremely quick action in the body and their wide availability make them one of the most common causes of poisonings worldwide, and they are often implicated in suicides in rural areas.
The use of phosphates in fertilizer, while less immediately toxic, is another aspect of modern agriculture with sometimes troubling side-effects. Phosphorus is often a limiting nutrient in marine ecosystems, and phosphate-rich runoff from over-fertilized fields is therefore often the cause of overgrowth, which manifests as algal blooms. At minimum, a sudden growth of algae, followed by its die-off and decay, consumes dissolved oxygen in the water, producing hypoxic conditions that kill off animals and plants in large numbers. In particularly concerning cases, the species of algae in the bloom are themselves dangerous, producing neurotoxins that kill marine life directly and also accumulate in seafood, leading to poisonings. Despite these problems, fertilizer remains the largest use of industrially produced phosphorus. The use of phosphates as chelating water softening agents, often to increase the effectiveness of detergents, is also known to contribute to harmful effects of phosphate on the environment.
Beyond fertilizers, poisons, and water-softening agents, there are a number of other phosphate compounds with important applications. Various inorganic phosphates are used as food additives, often as leavening agents. Trisodium phosphate is widely used in cleaning agents and disinfectants, and sometimes as a flux in ceramic glazes or solder. Zinc dithiophoshate is a common anti-wear additive used in automotive lubricants such as motor oil. Tricresyl and tributyl phosphates are important plasticizers, used to produce nitrocellulose, acyrlates, and PVC, and also serve as solvents in inks, resins, and adhesives. Glyophosphate, known commercially as Roundup, is an widely-used systemic herbicides. Other important organophosphorus compounds include organic derivatives of phosphine, the phosphorus analogue of ammonia, which itself is used to produce many specialty phosphate chemicals and as pesticides and fumigants.
Phosphorus has a number of other commercial uses. In addition to being used to produce fertilizers and various industrial phosphates, phosphoric acid may be used for rust removal as an etching agent in dentistry, or for the production of phosphoric acid fuel cells. Phosphazenes are nitrogen-phosphorus compounds used to produce hybrid organic-inorganic polymers that can be engineered to have highly desirable properties. These polymers have been used to produce drug-delivering gels that degrade in the body, polymer electrolytes with potential for use in fuel cells and batteries, and elastomers that can withstand a variety of chemical and thermal environments, which frequently find use in aerospace components. Pure phosphorus is also used directly in metallurgy to make phosphor bronze, and sometimes finds use as a dopant to manipulate the electrical properties of semiconductors. assistant' Reinterpretation of the Topic
Phosphorus, a nonmetallic element akin to nitrogen, exhibits a paradoxical nature. It is a crucial component of fundamental organic compounds such as DNA, ATP, and phospholipids, underscoring its indispensability to life. However, it is also a part of dangerous explosives and some of the most potent poisons known, such as organophosphate nerve agents. The dual nature of phosphorus is intertwined: its biochemical roles are enabled by the same chemical properties that make it highly reactive, while the deadly effects of nerve agents stem from their structural similarity to the natural targets of enzymes they irreversibly inhibit. This complex chemistry of phosphorus makes it versatile, defying simplistic characterizations.
Phosphorus, despite its omnipresence, was unknown as an element for much of human history due to its high reactivity preventing its natural occurrence outside compounds. Hennig Brand first isolated elemental phosphorus in 1669 while experimenting with urine in an attempt to create the philosopher's stone. Instead, he discovered a mysterious white substance that glowed in the dark, a phenomenon now understood to be a slow light-producing reaction with oxygen. Brand's discovery was eventually sold to D Krafft, who showcased the substance across Europe. The revelation that the substance was derived from urine led to its production by numerous other chemists.
The first commercial application of phosphorus was in matches. However, the early match industry was plagued with issues. White phosphorus, the form Brand isolated, was both highly unstable and toxic, leading to accidental fires and worker poisonings. In 1850, Anton Schrotter von Kristelli demonstrated that controlled heating could transform white phosphorus into a more stable, non-toxic red substance. Today, we know that elemental phosphorus can also form even more stable violet and black crystalline forms under temperature or pressure, although the red and white forms remain the most commonly used. The use of red phosphorus and various safety-enhancing design elements in "safety matches" enabled the widespread production and use of significantly safer phosphorus matches.
In 1769, Johan Gottlieb Gahn and Carl Wilhelm Scheele discovered that bones contained calcium phosphate and that the pure element could be extracted from bone ash. For the next seventy years, bone remained the primary source of the element. By the 1840s, bat and bird guano were recognized as another important source of phosphates, especially for use in fertilizers. Phosphate rock was also used as a phosphorus source as early as 1850, but this production method did not become significant until after the development of the electric arc furnace in 1890, which made the process considerably more feasible.
Phosphorus, a key element in modern industry, has a history that dates back to the World Wars. Its use in weaponry, particularly incendiary devices and smoke screens, was widespread due to its vigorous burning properties. Despite the horrific wounds it can inflict on human skin, phosphorus is still permitted in bombs and smoke-producing munitions. However, its use in direct bombardment is classified as a chemical agent and is thus prohibited.
Organophosphates, developed for warfare and considered illegal chemical weapons, are still stockpiled by many countries. These compounds, including VX and sarin gas, inhibit acetylcholinesterase, a crucial enzyme for normal nerve function. Interestingly, organophosphate pesticides, which operate through the same mechanism, are common in commercial agriculture. Their potency, rapid action, and wide availability make them a leading cause of poisonings worldwide.
Phosphates in fertilizers, while less immediately toxic, can have troubling side-effects. Phosphorus, often a limiting nutrient in marine ecosystems, can cause overgrowth or algal blooms when introduced via phosphate-rich runoff from over-fertilized fields. These blooms can consume dissolved oxygen in the water, leading to hypoxic conditions that kill off marine life. In some cases, the algae themselves produce neurotoxins, leading to further marine life deaths and potential seafood poisonings.
Phosphates also find use in various other compounds. Inorganic phosphates are used as food additives, trisodium phosphate in cleaning agents and disinfectants, and zinc dithiophosphate as an anti-wear additive in automotive lubricants. Tricresyl and tributyl phosphates serve as important plasticizers and solvents in various industries. Glyophosphate, known commercially as Roundup, is a widely-used herbicide.
Phosphorus also has other commercial uses. Phosphoric acid is used for rust removal, as an etching agent in dentistry, and in the production of phosphoric acid fuel cells. Phosphazenes are used to produce hybrid organic-inorganic polymers with highly desirable properties. These polymers have applications in drug-delivery gels, polymer electrolytes for fuel cells and batteries, and elastomers for aerospace components. Pure phosphorus is used in metallurgy to make phosphor bronze and as a dopant in semiconductors.
Phosphorous: Phosphorous is not typically obtained from minerals, but rather from phosphate rock.
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68. Arsenic - About Arsenic: Arsenic, an element with a rich history, is believed to have been first isolated by Saint Albertus Magnus, or Albert the Great, in 1250 AD. However, arsenic compounds were known even in ancient times, and it's possible that earlier alchemists also produced elemental arsenic. The name 'arsenic' has its roots in the Greek word 'arsenikon', which was derived from Syriac and Persian words for 'yellow orpiment', a naturally occurring arsenic(III) sulfide mineral.
Interestingly, arsenic has been used as both a medicine and a poison throughout history. Hippocrates prescribed orpiment for ulcers, and ancient Chinese medicine used arsenic compounds for various ailments. In the 18th century, Thomas Fowler popularized 'Fowler's solution', a potassium arsenite formulation sold as a remedy for diverse ailments like asthma, eczema, and malaria. Simultaneously, arsenic compounds were notorious poisons, used to eliminate pests and commit homicides in medieval Europe.
The use of arsenic as a poison declined after the introduction of the Marsh test in 1836, a reliable method for detecting arsenic in a deceased person. However, arsenic's toxicity continued to be exploited in modern times, with various arsenic compounds being used as pesticides, herbicides, and wood preservatives. Arsenic's deadly properties were even weaponized, with several chemical agents used in the first world war being arsenic compounds.
Modern medicine also employs arsenic-based treatments. Salvarsan, an arsenic-containing drug developed in the early 20th century, was used to treat syphilis until penicillin became available in the 1940s. Melarsoprol, another arsenic-containing drug, is still occasionally used to treat late stages of African trypanosomiasis, also known as African sleeping sickness.
Arsenic was historically used in metal alloys, with early bronze being made from arsenic and copper. Today, arsenic is primarily used in lead alloys to harden the soft metal, with such alloys being used in standard lead-acid car batteries.
Arsenic's modern uses also extend to semiconductors, with no historical precedent. Arsenic is a component of many III-V type semiconductors and semiconducting compounds with more complex formulations. The most common III-V semiconductor is gallium arsenide, developed in the 1960s, which has different electrical properties than silicon and is more suited to some applications.
In nature, arsenic is most commonly found in minerals in combination with sulfur and sometimes iron, nickel, or copper. The most common form of arsenic used in industry is arsenic trioxide, produced by roasting these minerals in air. Arsenic is rarely harvested directly, but rather produced as a byproduct of the mining and purification of other metal ores.
Arsenic: Arsenic is found in many minerals, including the arsenic mineral orpiment and realgar.
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69. Antimony - About Antimony: Antimony, a metalloid element, has been utilized by humans in various ways for thousands of years. As early as 3100 BCE, stibnite, an antimony trisulfide mineral, was used to produce kohl, the black eye makeup favored by Ancient Egyptian women. A vibrant yellow pigment produced from antimony trioxide and lead was used in glassware and paints starting around the 14th century BCE.
The first authors to describe a means of isolating metallic antimony were Italian metallurgist Vannoccio Biringuccio in 1540 CE and Georgius Agricola in 1556. French chemist Nicolas Lemery was the first to study the element and its compounds in depth, publishing his findings in 1707.
Medieval alchemists recognized antimony as a "mundane element" associated with feminity, and gave the element its own symbol. Antimony compounds had been used medicinally since the Ancient Greeks prescribed certain powders for the treatment of skin diseases. These compounds gained popularity as medicinal remedies known as "antimonials" in the years following the death of Swiss-German alchemist and physicist Paracelsus in the 16th century.
Like other elements including boron, silicon, germanium, arsenic, and tellurium, antimony is classified as a metalloid, having properties somewhere in between those of metals and non-metals. Though its chemical structure is closer to that of true metals, it is less thermally and electrically conductive, and has the unusual property of having a lower electrical conductivity as a solid than a liquid.
Some niche applications for antimony-based compounds do still exist in the field of medicine. However, with the slow recognition of the element's associated risks came a general shift in its applications towards primarily industrial and high technology uses. Antimony oxides and sodium antimonate are frequently used as flame-retardants in plastics, textiles, leather, and PVC.
Recent applications for antimony have focused on advanced semiconductor technologies. Particularly important are the compounds of antimony with indium, gallium, germanium, and tellurium, producing compounds such as InSb, Ge3Sb3, GaSb, and Sb2Te3. These semiconducting compounds are used as components of and as substrates for high-k dielectric materials in laser diodes, integrated circuits, infrared detectors, Hall-effect devices,and memory devices for data storage.
Antimony takes its elemental symbol Sb from stibium, the Latin name for stibnite; the origin of the name "antimony" is less clear. Its most common mineral sources are the aforementioned stibnite, found in hydrothermally formed veins, valentinite (antimony trioxide, a byproduct of the decomposition of stibnite), and tetrahedrite. Antimony is obtained primarily from stibnite during the production of silver, gold, and copper, and can also be recovered during recycling of lead-acid batteries.
Antimony: Antimony is sometimes found in pure form. It is also obtained from the mineral stibnite (antimony sulfide) and commonly is a by-product of lead-zinc-silver mining.
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70. Bismuth - About Bismuth: Bismuth, a p-block "poor metal," has a rich history and a plethora of applications that span from the ancient to the modern world. Despite being twice as abundant as gold in the earth's crust, bismuth remained largely unknown until the 15th century when German monk Basileus Valentinus referred to it as "wismut." It was not until the 16th century that Christian scholar Georgius Agricola distinguished bismuth from other similar metals like antimony, lead, tin, or zinc.
The name "bismuth" has several suggested origins, including bisemutum, Agricola's Latinized translation of wismut, and the Arabic bi ismid, meaning "possessing the properties of antimony." Early uses of bismuth compounds were mainly limited to medical treatments of digestive disorders and as additives to pewter alloys. However, its demand surged during World War I when it was utilized in solders and alloys, and again when it gained attention as an alternative to lead and cadmium due to its low toxicity.
Bismuth is unique in many ways. It is the most strongly diamagnetic of all metals, possesses the lowest thermal conductivity (with the exception of mercury), and exhibits the highest Hall Effect. It is also the heaviest element that is ostensibly stable. Bismuth occasionally occurs as a free element in nature and in minerals such as bismuthinite, bismite, and bismoclite.
Bismuth and its compounds have numerous applications. They are used in the automotive and aviation industries, safety devices in fire extinguishing systems, and solders. Bismuth is also used in malleable irons, steels for free machining, and isostatic lead-bismuth eutectic (LBE) used in nuclear reactors. The most common medical use of bismuth is in the commercial digestive aid bismuth subsalicylate, more commonly known as Pepto-Bismol.
In the realm of advanced and emerging technologies, crystalline bismuth compounds play a crucial role. Bismuth telluride is a semiconductor that exhibits the thermoelectric effect when alloyed with antimony or selenium. Bismuth selenide is a topological insulator, a unique hybrid material with an insulating core and conductive surface with applications in spintronics-based electronics and quantum computers. Researchers have identified superconducting bismuth compounds like silver-doped bismuth oxysulphide and bismuth strontium calcium copper oxide (BSCCO), one of several materials that exhibits the highest measured superconducting transition temperatures. Bismuth Ferrite (BFO) is a perovskite crystal that is piezoelectric, multiferroic, and can act as a nanoscale shape memory material for integrating photonic and electrical components in plasmonic devices or used in high-temperature supercapacitors for electric vehicles.
Bismuth: Bismuth is often found in pure native form, as well as in the mineral bismuthinite. It is chiefly obtained as a by-product of copper, lead, tungsten, and molybdenum processing.
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71. Moscovium - About Moscovium: Moscovium (Mc), previously referred to as Ununpentium (Uup), is a superheavy element that belongs to the P-Block, Group 15, and Period 7 of the periodic table, bearing the atomic number 115. The existence of Moscovium was first reported in 2004 by a collaborative effort between Russian scientists at the Joint Institute for Nuclear Research in Dubna, Russia, and American scientists at the Lawrence Livermore National Laboratory in Livermore, California, USA. This discovery was officially recognized by the International Union of Pure and Applied Chemistry (IUPAC) in 2015.
The synthesis of this superheavy element was achieved by bombarding americium-243 with calcium-48 ions. The element was named Moscovium, a tribute to the Moscow Oblast, where the Joint Institute is located.
Moscovium is a highly unstable element, and only a few of its properties have been observed. However, based on its position in the periodic table, it is expected to share characteristics with the pnictogen group of elements (group 15), which includes elements like bismuth.
Moscovium: Moscovium is a synthetic element that is not found naturally. It is produced by bombarding atoms of americium with ions of calcium in a cyclotron.
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72. Oxygen - About Oxygen: Oxygen, a ubiquitous and vital element, was not as easily discovered as one might assume. For centuries, scholars recognized the importance of air in combustion and respiration, but a comprehensive understanding of the chemistry underlying these processes remained elusive until the late 18th century.
The phlogiston theory, an early chemical theory, posed a significant obstacle to this understanding. This theory proposed that all combustible materials contained a substance called phlogiston, which was released during burning. Carl Wilhelm Scheele and Joseph Priestley, however, isolated a component of air that supported combustion and respiration longer than ordinary air. Scheele referred to it as "fire air," and Priestley called it "dephlogisticated air," both assuming it was the substance that combined with phlogiston during combustion. This gas was, in fact, oxygen. Priestley is typically credited with its discovery, as he was the first to publish his synthesis method in 1774, even though Scheele isolated his "fire air" first in 1771. Antoine Lavoisier was the third chemist who recognized that the newly discovered gas was a new element and published the first correct explanation of combustion in 1777. Lavoisier named the element from the Greek roots oxys, acid, and genes, producer, based on his mistaken theory that all acids contained this new element. Despite this belief being proven incorrect, the name oxygen had stuck.
Oxygen's versatility baffled early chemists. As a strong oxidizing agent, oxygen reacts with nearly any element at sufficiently high temperatures. It is found in water, most organic compounds, and forms both single and double bonds. It is present in many polyatomic ions and forms complexes with transition metals like iron. Major ores of iron, zinc, and aluminum are all oxides, as is the quicklime used in mortar and concrete, the carbon dioxide produced by aerobic respiration, and common silica sand.
Oxygen has limitless uses in its compound forms and many applications as a pure element. The most stable and common allotrope of oxygen is the O2 we breathe. Pure oxygen gas is traditionally extracted from liquefied air through fractional distillation. It is also used for life support in aerospace and diving contexts, as rocket fuel, as a reagent in the chemical industry, and in metallurgy. In steel smelting, injecting pure oxygen removes sulfur impurities and excess carbon as oxides.
Ozone, another form of oxygen composed of three oxygen atoms, is an extremely potent oxidizing agent. It is produced in small amounts from molecular oxygen, most commonly from the action of ultraviolet radiation on fossil fuel byproducts in the air, and from the electrolysis of air. Ozone's reactivity makes it toxic, but it decays to harmless oxygen, making it useful for disinfection. It is used to kill insects in grain, spores in food processing plants, and bacteria on food and surfaces. It also reacts with many water contaminants and can be used in water treatment plants to both kill biological agents and neutralize chemical toxins. Ozone's instability requires that it be produced on site, typically using high-voltage electrolysis of air, or through the use of ultraviolet ozone generators.
Oxygen: Oxygen is the most common element on the surface of the Earth, occurring as oxygen gas, in water, and oxide minerals, or in combination with elements in silicates, carbonates, phosphates, sulfates, and many others.
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73. Sulfur - About Sulfur: Sulfur, a plentiful element often found in its elemental state, has been recognized and utilized extensively throughout human history. In fact, alchemists considered sulfur as one of the three fundamental substances that composed everything in the universe. The term "sulfur" originates from a Latin root meaning "to burn", and was historically used to describe flammable substances. Sulfur's earliest recorded uses were in traditional medicine, fumigation, and cloth bleaching. It was later produced in large quantities for use in gunpowder. In the dawn of chemistry, sulfur was thought to be a compound, but in 1777, Antoine Lavoisier, often referred to as the father of modern chemistry, convincingly argued that it was an element, a view that soon became widely accepted.
The primary use of sulfur is in the production of sulfuric acid, a chemical so integral to modern industry that its consumption is considered a reliable indicator of a nation's industrial development. In industrial chemistry, it is used in the production of ammonia, aluminum hydroxide, phosphate fertilizers, alums, dyes, and refined petroleum products. It also serves as an acid catalyst and an industrial cleaning agent. Furthermore, it is a major component of lead-acid batteries found in most automobiles, as well as some household drain cleaners. It is a component of the sulfur-iodine cycle, a process proposed for the production of hydrogen as fuel.
Various forms of sulfur are important chemical reagents. Elemental sulfur is a necessary component of vulcanized rubber, which is stabilized by disulfide bond crosslinking. Carbon disulfide is an important organic chemistry reagent, used as an industrial non-polar solvent and a key player in the manufacture of polymers such as cellophane and rayon. Sulfur dioxide can be used as a bleaching agent for paper and delicate fabrics, and in wastewater treatment to remove chlorine. Many sulfur compounds, including the common sodium lauryl sulfate, serve as detergents and surfactants, found in everything from personal care products such as shampoo to lab reagents used in molecular biology. Hydrogen sulfide is an important intermediate used to produce metal sulfides and organosulfur components. Sulfur hexafluoride is a gaseous dielectric used in high-voltage circuit breakers and switchgear, as well as in the high-voltage power supplies for scientific equipment such as particle accelerators and electron microscopes. It is also used as an etchant in semiconductor manufacturing, a tracer compound of use for studying spread of toxic agents through the air. Phosphorus sesquisulfide is used to produce "strike anywhere" matches, while other sulfides are used in the production of safety matches.
While elemental sulfur is not toxic to humans, it can be used as a pesticide. Additionally, many sulfur compounds are used for their toxicity to microbes. Sulfur compounds have long been used in winemaking to prevent the souring caused by bacterial growth during fermentation, and sulfites are often used to preserve food, particularly dried fruit and molasses. Gaseous sulfur compounds that do exhibit toxicity to humans have a history of use in warfare; mustard gas is one example.
Sulfur compounds also play a significant role in the technology industry. Several types of lithium-ion batteries utilize sulfur compounds, and sodium-sulfur batteries are used in large-scale energy storage applications. Additionally, many sulfide compounds are semiconductors that are either in active use or are the subject of current investigation. Cadmium sulfide is used primarily as a pigment, but can also be used in photoresistors, thin film transistors, and semiconductor lasers. Iron pyrite is abundant, cheap and had favorable chemistry for use in solar cells, though fabrication of actual cells has faced many challenges. Copper zinc tin sulfide is also of interest for use in photovoltaics, particularly in thin film device designs. Molybdenum disulfide, like the nanomaterial graphene, can be grown in layers a single atom thick and is of interest for use in many optoelectronic applications.
As the tenth most abundant element in the universe, sulfur is omnipresent. In addition to being found in native deposits, often in regions with volcanic activity, sulfur is a component of sulfide and sulfate minerals, including many which serve as primary ores for the metals they also contain. Some of these minerals are used directly-for instance gypsum, a natural mineral form of calcium sulfate, is both mined directly and recovered as byproduct of other industrial processes for use as a major component of drywall, plaster, and cement. Elemental sulfur may be extracted from many of these minerals or from pure deposits, but today most industrial sulfur production is a side product of other processes, especially the refining of petroleum products, which in their unprocessed form often contain significant amounts of organosulfur compounds.
Sulfur: Sulfur is mined from pure sulfur deposits found in oil-producing regions in Louisiana, Texas, Canada, and Mexico. It is also found in pure form near volcanoes and hot springs.
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74. Selenium - About Selenium: In 1817, chemists Jons Jakob Berzelius and Johan Gottlieb Gahn embarked on an investigation of a peculiar red precipitate discovered by workers at their jointly-owned sulfuric acid plant. Initially mistaken for arsenic, the substance was later thought to be tellurium due to the distinctive odor it emitted when burned. However, further examination revealed that it was neither, leading the chemists to the realization that they had stumbled upon a previously unknown element. Drawing parallels between the newly discovered element and tellurium, whose name translates to "earth", Berzelius named the new element Selenium, after Selene, the moon.
Selenium, a semiconductor, can adopt various crystalline structures based on the conditions of its formation. The brick red powder discovered by Berzelius and Gohan is the form most commonly encountered as a result of chemical reactions. When rapidly melted, it yields a black vitreous solid often sold industrially, but its most stable form is a dense grey solid. In 1873, Willoughby Smith demonstrated that the electric resistance of grey selenium predictably varies with incident light, a property known as photoconductivity. This property is also exhibited by tellurium, albeit to a lesser extent. Selenium's earliest major applications were in semiconductor devices such as rectifiers in radio and television tubes, which served as replacements for the previously used vacuum tubes and precursors to today's silicon-based components.
Despite the dominance of silicon as the primary industrial semiconductor, selenium continues to hold relevance in semiconductor technologies. While most selenium rectifiers have been superseded by other technologies, selenium is still employed in surge protection devices in some high-energy DC circuits. As a component of compound semiconductors like copper indium gallium selenide (CIGS), indium selenide, gallium selenide, cadmium selenide, and zinc selenide, selenium is crucial for the production of many thin-film solar cells. It is also found in electro-optical devices such as LEDs, lasers, and photoresistors. Recently, researchers have shown considerable interest in the potential use of cadmium selenide nanocrystals, known as quantum dots, in innovative solar cells, more efficient LEDs, and biomedical imaging applications.
Pure amorphous selenium was once a staple component of every photocopier, where its photoconductive properties facilitated the production of images based on the areas of light shining through a printed document. Today, organic photoconductors have largely replaced selenium in this role. However, selenium can also produce images based on exposure to x-rays. These images can either be transferred to paper, as in a photocopier, or read directly from charge patterns on the selenium into a computer via a thin film transistor array. This type of x-ray technology, which never gained popularity during the era of x-ray films, has seen renewed interest with the advent of digital x-ray imaging systems. As a result, amorphous selenium is now found in many flat-panel digital x-ray machines used for medical and dental imaging.
Beyond its role as a photoconductive semiconductor, selenium serves several key functions. As a component of cadmium sulfoselenide pigments, it can impart a brilliant ruby red hue to materials. In glassmaking, small amounts of selenium salts are added to counteract the green tinge caused by iron impurities. Selenium is also a component of metal alloys, where it enhances the machinability of the final material and often substitutes the more toxic metal lead.
Although excessive quantities of selenium can be toxic, the element is also an important micronutrient, serving as a necessary cofactor for several enzymes. Due to this key biological role, selenium is sometimes included in nutritional supplements. Notably, the primary mechanism of mercury poisoning is the permanent inactivation of these essential enzymes caused by a reaction between mercury and selenium. Therefore, the effects of certain types of mercury exposure can be partially mitigated by sufficient selenium intake.
Selenium is primarily produced as a byproduct of copper refining, but it is also recycled from scrap.
Selenium: Selenium is typically obtained as a by-product in refining lead, copper, tin, silver, and gold ores.
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75. Tellurium - About Tellurium: Tellurium, a brittle, silver-white, semiconducting metalloid, was discovered by Franz Joseph Muller in 1782. Initially mistaken for antimony, it was later identified as a new element by Martin Heinrich Klaproth in 1798, who named it "tellurium", signifying "earth".
Tellurium's unique electrical properties make it a key component in semiconducting compound materials. For instance, cadmium telluride is used in thin film solar cells, offering an environmentally friendly and cost-effective alternative to traditional silicon cells. Cadmium zinc telluride finds applications in solar cells, radiation detectors, terahertz wave generation and detection devices, electro-optic modulators, solid-state x-ray detectors, and photoreactive gratings. When doped with tellurium, zinc selenide becomes a scintillator material used in x-ray and gamma ray detectors. Bismuth telluride and lead telluride are thermoelectric materials used in refrigeration and portable thermal generators.
In the realm of technology, tellurium plays a significant role in the form of chalcogenide glasses. These glasses, made using sulfur, selenium, or tellurium compounds, exhibit high refractive indices and non-linear optical effects, making them ideal for use in optical fibers for telecommunications, lasers, photonic integrated circuits, and other optical applications. Certain chalcogenide glasses, such as GeSbTe and AgInSbTe, undergo predictable changes in crystal structure driven by thermal energy, a property exploited in rewritable optical disks and phase-change computer memory.
Tellurium also serves as an additive to metal alloys, primarily to improve the machinability of steel or copper, and to enhance the strength and durability of lead. It is also found in some forms of cast iron. Telluride compounds may be used as pigments to color ceramics, as components of blasting caps, or as catalysts for some industrial chemical processes.
Despite its rarity, tellurium is commercially produced mostly from byproducts of electrolytic copper refining. It is also occasionally recovered from old devices which contained it, most often outdated photocopiers.
Tellurium: More than 90% of tellurium has been produced from anode slimes collected from electrolytic copper refining, and the remainder was derived from skimmings at lead refineries and from flue dusts and gases generated during the smelting of bismuth, copper, and lead-zinc ores.
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76. Polonium - About Polonium: Polonium, a metalloid, was first discovered by Marie and Pierre Curie in 1898 through the reduction of uranium ores. Despite its scarcity on Earth, with only 100 micrograms of polonium produced from one ton of uranium ore, it has found a variety of applications due to its unique properties.
Polonium is primarily produced through neutron bombardment of bismuth (209Bi) in a nuclear reactor, resulting in 210Bi which decays to 210Po after 5 days. This isotope, like many other radioactive elements, is used in radioisotope thermoelectric generators and played a significant role in the Manhattan Project, being a key ingredient in the detonator for the plutonium bomb, "Fat Man".
Polonium also serves as a characteristic neutron source and is used in antistatic devices in industries. It is often present in brushes designed to minimize static electricity generated when rolling paper, wire, or sheet metal. However, due to its short half-life, these industrial tools need to be replaced regularly. Traces of 210Po can be found in cigarettes, agricultural phosphate fertilizers, seafood, and even in indoor air. It is presumed to be the cause of the majority of the 15,000-22,000 estimated lung cancer deaths in the United States every year attributed to radon.
Polonium can readily form compounds with many other elements, although most polonium compounds are synthetically created with limited applicability outside of the scientific community. Polonium has 33 observed isotopes, all of which are radioactive. The most stable isotope is 209Po with a half-life of 103 years, which decays into lead through alpha decay. However, the most common isotopes of polonium are part of the naturally-occurring uranium decay chain and are found in trace amounts throughout Earth's biosphere.
Polonium: Polonium is a decay product of uranium. It is found in minute amounts in uranium ore. It is artificially created by bombarding bismuth with neutrons.
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77. Livermorium - About Livermorium: Livermorium, previously known as Ununhexium with the symbol Uuh, is a man-made superheavy element. It first came into existence in 2000, thanks to the efforts of the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. The Lawrence Livermore National Laboratory team also contributed to the research on this element.
Despite the initial proposal to name the element Moscovium, the International Union of Pure and Applied Chemistry (IUPAC) decided to honor the Lawrence Livermore laboratory by naming the element after it.
Livermorium, being the heaviest member of group 16 in the periodic table, is expected to share chemical properties with other members of this group. It is predicted to be most similar to Polonium, its closest neighbor in the table.
However, the production of Livermorium atoms has been extremely limited, hindering comprehensive studies of its properties and any potential practical applications. Despite these challenges, the creation of Livermorium has opened up new frontiers in the exploration of superheavy elements.
Livermorium: Livermorium is a synthetic element that is not found naturally.
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78. Fluorine - About Fluorine: Though its primary ore, fluorite, has long been used in smelting to reduce the melting point of metal ores, fluorine was the last of the halogens to be isolated. Hydrofluoric acid was commonly used as a glass etching agent by the eighteenth century, but it was not until 1810 that Sir Humphry Davy proved that this acid was analogous to hydrochloric acid and therefore must contain an element similar to chlorine. However, the methods used to isolate chlorine were not successful in isolating fluorine, instead resulting only in frustration and sometimes the lethal hydrofluoric acid poisoning of many chemists who attempted to do so. Ferdinand Frederic Henry Moissan finally produced the pure element in 1886 with a method still in use today. The name for the element was derived from that of its ore, which itself had been derived from the latin fluere, meaning "to flow"--a reference to the effect the ore had on molten metal. Moissan was awarded the Nobel Prize in Chemistry for his achievement in 1906.
Fluorine's earliest function, serving as a flux, remains vital in modern industry. Fluorine compounds are used in this capacity in steelmaking, welding, glassmaking, and in producing some forms of ceramics and cements. Additionally, the fluorine-containing compounds sodium hexafluoroaluminate and aluminum trifluoride are absolutely essential fluxes used in the extraction of aluminum from bauxite. Without the use of these compounds, the temperature required for this process would be too high for aluminum metal to be an economically viable industrial material.
Fluorine is also an important industrial tool in the form of hydrofluoric acid. Though considered a weak acid in dilute solution, as hydrogen and fluorine tend to remain bound rather than dissociating into ions under these conditions, hydrofluoric acid is highly corrosive. Its unusual ability to eat away even at glass led to its first use in glass etching. It is also used to etch the tough ceramics used in dental implants, as this improves the ability of the ceramic to be bound to other materials using adhesives. In steelmaking, hydrofluoric acid often serves as a pickling agent, removing oxides and other impurities on the surface of the metal. Hydrofluoric acid is also used in the production of extremely strong acids known as super acids, and in producing intermediate fluorine compounds used in the production of organochlorines and other fluorine products.
Organofluorine compounds are ubiquitous in modern industry. By volume of production, the most common type of organofluorine compounds are refrigerant gases. These include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). These are used primarily for refrigeration and air conditioning, but are also found as aerosol propellants and solvents. CFCs were the first of these to be used, but were replaced by HCFCs when they were found to cause depletion of the ozone layer. Unfortunately HCFCs still cause ozone depletion, but to a lesser degree. HFCs cause little or no ozone depletion, and are therefore prefered to HCFCs when applicable. Another useful class of organofluorine compounds are the perfluorocarbons (PFCs). PFCs may be used as surfactants, or in the production of fluoropolymers such as Teflon. Teflon and related fluoropolymers are perhaps best known for use in non-stick coatings on cookware, but they are additionally used as insulating wire coating, friction reducing coatings on mechanical parts, and as Gore-Tex, a microporous polymer membrane that finds use in rain-repelling clothing, filters, and packing seals.
Additionally, fluorine-carbon bonds are often used in pharmaceuticals and to make organic agrichemicals such as pesticides more chemically stable. In drug design, this is often necessary because the non-fluorinated compound degrades too quickly in the body to have the desired effect. As such, many common pharmaceuticals are fluorinated, including SSRIs, quinolone antibiotics, and many steroids and anesthetics. However, the stability of organofluorine compounds is not always positive--these compounds tend to persist in the environment and to bioaccumulate. As many organofluorine agrichemicals and some common industrial organofluorines are toxic, this is a significant environmental concern.
Fluorine has a few other major uses in medicine. The isotope fluorine-18 is used as a tracer in positron emission tomography (PET). This type of medical imaging detects relative concentrations of a radioisotope that has been chemically bound to a biologically active molecule, most often glucose, to trace the accumulation of said compound in various body tissues. Glucose is used because more metabolically active areas of the body consume more glucose. In the brain, this is used to monitor which areas are most active, while in whole body scans this is typically used to detect cancer cells, which consume glucose at a disproportionately high rate compared to surrounding tissue. Additionally, fluoride compounds are used in toothpaste and added to drinking water, as the fluorine reacts with and hardens tooth enamel, reducing rates of cavities.
Due to the extreme reactivity of fluorine gas, most fluorine chemistry makes use of less-reactive intermediates rather than elemental fluorine, but the gas is produced for a few industrial processes. The vast majority of fluorine gas is used to produce either uranium or sulfur hexafluoride. Sulfur hexafluoride is used widely as a gaseous dielectric medium in high-voltage circuit breakers and other electrical equipment, often replacing old devices that contained harmful PCBs, while uranium hexafluoride is used in the production of nuclear fuels. The remainder of fluorine gas produced is used in the production of nitrogen fluoride, several metal fluorides, and fluorinating agents for use in organic synthesis. The gas nitrogen trifluoride is used in the cleaning of chambers used in the production of many electronics, in chemical lasers, and in plasma etching of silicon wafers. Rhenium hexafluoride and tungsten hexafluoride are used as precursor materials in chemical vapor deposition. Halogen fluorides such as chlorine and bromine trifluoride and iodine pentafluoride, as well as sulfur tetrafluoride, are common fluorinating agents used in the production of industrial fluorocarbons and fluorinated pharmaceuticals.
As the early chemists who worked with fluorine quickly learned, its unique properties present significant difficulties and dangers. Fluorine-fluorine bonds are relatively weak, while the bonds between it and other elements are usually very strong, due to fluorine's high electronegativity; this combination makes fluorine gas extraordinarily reactive. It is corrosive to substances usually considered profoundly inert, including glass, and is therefore stored only in containers made from metals that acquire a passivating metal-fluorine compound coating upon contact with the gas--typically nickel or nickel-alloys. Hydrofluoric acid causes both severe burns and poisoning upon exposure, the latter occurring as it easily diffuses through skin and the fluorine quickly binds with essential ions. However, despite the risks and difficulties inherent to working with fluorine and some of its compounds, it remains a powerful chemical tool, and component of vital materials.
Fluorine is produced directly from the calcium fluoride mineral fluorite, sometimes also known as fluorspar. Lower grade deposits, termed "metspar", are typically used directly in flux applications, while higher grade deposits known as "acid spar" are treated with sulfuric acid to produce hydrofluoric acid. This acid is then used in the production of virtually all other fluorine compounds. For the few applications in which elemental fluorine is required, it is still prepared via the original method devised in the nineteenth century: the electrolysis of a mixture of hydrogen fluoride and potassium fluoride, the latter being added to allow the mixture to conduct electricity. Additionally, fluorosilicic acid is a byproduct of phosphoric acid production, and this compound is increasingly being recovered as a secondary fluorine source.
Fluorine: Fluorine is obtained mainly from the mineral fluorite or fluorspar (calcium fluoride). Other fluorine-bearing minerals include apatite and cryolite.
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79. Chlorine - About Chlorine: Chlorine, known for its distinctive yellow-green color, has a storied history. As early as the 14th century, alchemists used hydrochloric acid, a form of chlorine, in their experiments. In 1774, Carl Wilhelm Scheele documented the production of a corrosive gas, later identified as elemental chlorine, from a reaction of hydrochloric acid with magnesium oxide. Despite the initial misunderstanding of its chemistry, chlorine gas found practical use quickly. By 1785, Claude Berthollet was using it to bleach textiles, and soon after, calcium and sodium hypochlorites were widely used as textile bleaches and disinfectants. The elemental nature of chlorine gas was finally understood in 1810, thanks to Sir Humphry Davy's experiments.
Throughout the 18th century, chlorine found additional applications. The photosensitivity of silver halides, including silver chloride, was exploited for photographic image production starting in 1839. The organochlorine compound chloroform was first used as an anesthetic in 1847. The introduction of the chloralkali process in 1892 enabled the first industrial-scale production of chlorine, leading to its widespread use in bleaches, antiseptics, and photography, as well as expanded use in industry.
Today, millions of tons of chlorine are produced and used each year, reflecting its enormous importance in modern industry. A significant percentage of this chlorine is used directly in the production of polyvinyl chloride (PVC), a versatile plastic used in everything from water pipes to clothing. Additionally, a substantial amount of chlorine is processed to hydrochloric acid, an industrial chemical used in steel production, petroleum product desulfurization, pH modification in oil wells, latex coagulation, and various forms of food processing, including sugar refining.
Hydrochloric acid is also used to produce many other important chlorine chemicals, including metal chlorides and chlorosilanes. Metal chlorides have many uses, from nickel electroplating to water treatment. Chlorosilanes are essential for producing high-purity silicon used in the semiconductor industry and in silicone production.
Organochlorine compounds, produced using various chlorine-containing reagents, have a vast range of functions. Low molecular weight chlorinated hydrocarbons such as chloromethanes and tetrachloroethylene are vital non-polar solvents used in applications such as degreasing and dry cleaning. A number of important herbicides and detergents are also organochlorine compounds.
Chlorofluorocarbons (CFCs) and polychlorinated biphenyls (PCBs) are classes of organochlorine compounds that were once widely used but have since been largely phased out due to their potential for damage to health and the environment. CFCs were used as refrigeration fluids, propellants in aerosols, and as solvents, but were found to cause significant damage to the earth's ozone layer. They have since been replaced in most applications by the much less damaging hydrofluorocarbons (HFCs). PCBs, once used as plasticizers, fire retardants, and coolants, have now been completely banned in some countries, while others have significantly limited their use.
Chlorine's relationship to biological organisms is somewhat paradoxical. Chlorine ions, usually obtained in the form of sodium chloride-table salt-are absolutely necessary for life. However, chlorine in the form of gas, concentrated hydrochloric acid, or many other chlorine compounds is quite toxic. Chlorine gas has been used as a chemical weapon, and many other chemical warfare agents are chlorine compounds.
Additionally, many organochlorine compounds are both toxic and known to persist for long periods in the environment. For this reason, many such compounds have been either withdrawn from use entirely or tightly regulated. The United Nations Environmental Program produced a list of twelve "dirty dozen" persistent organic pollutants (POPs) of particular concern in 2001; all of which are chlorinated organic compounds. However, it must be noted that the problems with many chlorine compounds-their toxicity and tendency to persist in biological systems-are intimately tied to the advantages of using chlorine in many applications. In pharmaceutical manufacturing, carbon-chlorine bonds enable a drug to remain intact and active in the body for longer periods, while chlorine disinfectants directly exploit the reactivity and resultant toxicity of some chlorine products. It is therefore vital that use of chlorine products be managed responsibly, as their associated risks can never be completely eliminated.
The most common natural chlorine compound, sodium chloride, maybe be mined as rock salt or produced from evaporated saltwater. Much rock salt is used directly for deicing roads and sidewalks, and additionally some salt is simply processed to suitable forms for use in food. The rest is processed using the chloralkali process, producing both chlorine gas and sodium hydroxide through the electrolysis of brine. Very pure hydrochloric acid is produced by reacting chlorine and hydrogen gases. Additionally, hydrochloric acid is produced as a byproduct of many organic synthesis reactions, and therefore a significant quantity of technical and industrial grade hydrochloric acid are recovered from industrial chemical processes.
Chlorine: Chlorine is obtained by the electrolysis of sodium chloride solutions. Along with sodium, chlorine is abundant in the oceans. Chlorine is present in small amounts in many minerals. The most common chlorine-bearing mineral is halite (sodium chloride).
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80. Bromine - About Bromine: Bromine, a nonmetallic element known for its strong, unpleasant odor, was discovered independently by two chemists, Carl Jacob Lowig in 1825 and Antoine Balard in 1826. Balard extracted bromine from seaweed ash using a method commonly used to obtain iodine at the time. Lowig, on the other hand, experimented with a concentrate from a mineral water spring in his hometown. He saturated this concentrate with chlorine and then extracted it using ether. After the ether evaporated, a foul-smelling brown liquid remained. Lowig used this liquid to demonstrate his skills and secure his first position in an academic chemistry lab. The name bromine, derived from the Greek word for "stench," was given to the new element after Balard published his results and they were confirmed by senior chemists.
Bromine's first significant commercial use was in photography, starting in the mid-nineteenth century. Silver bromide, like other silver halides, is a light-sensitive crystal. It can be used alone or with silver chloride to produce film capable of recording an image when exposed to light. Shortly after bromine was introduced for use in photography, potassium and sodium bromides were used as anticonvulsants and sedatives. However, due to the toxicity of these compounds, they were largely replaced as other drugs became available. Occasionally, potassium bromide is still used as an epilepsy treatment in veterinary medicine. The toxicity of some bromine compounds was deliberately exploited for use in chemical warfare during the First World War. Compounds such as xylyl bromide, similar to many more familiar chlorine-based chemical warfare agents, cause severe irritation to skin and mucous membranes, leading to pain, tearing, respiratory distress, and sometimes chemical burns.
In modern usage, inorganic bromine compounds are primarily found in a few areas beyond film photography. Calcium, sodium, and zinc bromides are all used in drilling fluids in oil and natural gas mining. Bromine gas, hydrogen bromide, or other simple bromine compounds can be used to reduce mercury pollution from coal power plants. Like chlorine, bromine can be used in the maintenance of swimming pools and spas. It is usually produced as needed for this use from a bromide and hydrogen peroxide. Bromine may also be used for drinking water disinfection, though in this usage it is typically supplied in the form of a polybrominated resin cartridge that is inserted into water treatment systems.
Bromine is also important in organic synthesis. In this usage, the original source of bromine is an inorganic compound-bromine gas or hydrogen bromide-but except in cases where hydrogen bromide acts solely as a catalyst, ultimately the bromine is incorporated into an organic bromide compound. These compounds often serve as intermediate reagents in multistep synthesis of complex organic molecules such as pharmaceuticals. One notable class of such reagents are Grignard reagents, magnesium halides attached to carbon compounds. Additionally, some organobromine compounds are themselves end products used in a variety of applications.
Synthetic organobromine compounds are used as pharmaceuticals, dyes, flame retardants, and pesticides. Bromated pharmaceuticals are far less common than organofluorine or organochlorine drugs, but nonetheless several such drugs are in current use as vasodilators, sedatives, chemotherapeutics, and antiseptics. The earliest bromine dye in use was actually a natural organobromine produced by a family of sea snails. This dye, Tyrian purple, was prized for being colorfast despite weathering and sunlight, and its scarcity made objects dyed with it luxuries and status symbols in ancient times. Today, bromine-substituted dyes are used in commercial textile coloring as well as in analytical chemistry as pH indicators and in molecular biology to bind to and visualize DNA. The use of organobromine flame retardants and pesticides is widespread but controversial, as many of these compounds are known to breakdown extremely slowly, and therefore they act as persistent organic pollutants. The persistence of these compounds is of particular concern because many are ozone depleting agents, and some are known to be toxic to humans or have the potential to act as hormone-disruptors.
Bromine is recovered from naturally bromine-rich brines which are frequently found in underground rock formations. The bromine can be recovered from these brines by treating them with chlorine gas. Additionally, bromine can be recovered as a byproduct of organic synthesis reactants using brominated reagents, or from incineration of bromine-containing plastics.
In summary, bromine is the only liquid halogen. Bromide compounds are formed when a metallic cation binds with a charged (- 1) bromine (Br) anion to form a bromide salt of that metal. Metallic bromides are marketed under the trade name AE BromidesTM. Most metal bromide compounds are water soluble for uses in water treatment, chemical analysis and in ultra high purity for certain crystal growth applications. Bromide in an aqueous solution can be detected by adding carbon disulfide (CS2) and chlorine. Bromides were first prepared and used as a sedative, which is why overused platitudes or phrases are sometimes called bromides.
Bromine: Bromine is recovered from seawater, sea salts, and evaporite deposits in small quantities. It is also found in brines in wells in Michigan and Arkansas.
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81. Iodine - About Iodine: Iodine, a nonmetallic element recognized for its distinct violet vapor, was discovered by two chemists, Bernard Courtois in 1811. Courtois, while producing saltpeter, accidentally added an excess of sulfuric acid to sodium carbonate extracted from seaweed. This resulted in a cloud of purple vapor which condensed to form a shiny crystalline substance on cold surfaces. Recognizing the significance of his discovery, Courtois, who suspected he had discovered a new element, passed the material on to two chemist friends. Their investigations were published in 1813 and confirmed by renowned chemists. One of them, Joseph Gay Lussac, suggested the name be derived from iodes, Greek for violet, due to the color of iodine's vapor.
In many ways, iodine shares properties with the lighter members of the halogen family: fluorine, chlorine, and bromine. Like other halogens, iodine in elemental form exists as a diatomic molecule. Its compound with hydrogen, hydriodic acid, is a strong acid and a useful chemical reagent, particularly for its role in the industrial production of acetic acid. Hydroiodic acid is also used to produce other useful iodine compounds, particularly alkyl halides, which are important in organic synthesis. Silver iodides, like other silver halides, are light-sensitive, a property exploited in film photography. Both bromine and iodine can be used in metal halide and halogen lamps, though designs using iodine are more common.
Unlike other halogens, iodine is solid at room temperature and less reactive due to its lower electronegativity. This lower reactivity makes it less toxic in elemental form than the lighter halides. While fluorine, chlorine, and bromine cause burns upon contact with tissue, elemental iodine is considered an irritant and requires prolonged contact with skin to cause significant damage. This allows the use of iodine solutions as topical disinfectants, often used to clean skin prior to surgery. Elemental iodine is not particularly soluble in water, so these solutions typically include solubilizing agents in addition to iodine. Iodine also has unique uses in various analytical chemistry procedures, particularly the detection of glucose polymers such as starch. Iodine-impregnated polymer films are used as cost-effective light polarizing optical filters found in products such as LCD screens, sunglasses, and optical microscopes.
Iodine's other unique applications relate to its role as an essential nutrient. Iodine is a necessary component of the thyroid hormones T3 and T4, which regulate metabolic rate. Iodine deficiency causes enlargement of the thyroid gland, a condition known as goiter, as well as the myriad symptoms of hypothyroidism. Many populations lack access to sufficient dietary iodine, and many nations now mandate that table salt be treated with iodine salts to prevent endemic goiter. This is generally considered one of the simplest and most effective public health measures, as iodine deficiency is a leading cause of intellectual and developmental disabilities.
Iodine salts are common in nature, but relatively few sources of iodine are useful commercially. The most common source is brines that collect in used oil and gas wells, which may be purified and treated to produce iodides. The iodides are then reacted with chlorine to produce the pure element. The only other commercial source of iodine is caliche mineral formations in Chile; these are primarily mined for the extraction of sodium nitrate, but iodates and iodides are recovered as byproducts.
Iodine: Iodine is not typically classified as a mineral, but it can be found in various food sources.
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82. Astatine - About Astatine: Astatine, a radioactive element, is the second rarest naturally-occurring element on the periodic table after berkelium, and the rarest of the non-transuranic elements. With less than one gram present on earth at any given time, only six of astatine's 37 known isotopes are naturally occurring. These trace amounts of isotopes with atomic numbers 214-219 are produced via decay chains of heavier elements like francium and polonium and/or exist in equilibrium with isotopes of uranium, thorium, and neptunium. Its most stable isotope is 210-At, which has a half-life of 8.1 hours and decays to polonium-210; the least stable is 213-At, which decays to the bismuth-209 after only 125 nanoseconds. Given its quick decay, the element has proven difficult to study. Any quantity of astatine sufficient to constitute a solid would vaporize instantaneously from its radioactive energy, so many of its properties are either unknown or estimated. The element is generally considered to be a member of the halogen family based on observed properties obtained via mass spectrometry and radioactive tracer experiments with dilute astatine solutions; it behaves similarly to iodine, though it is more metallic.
Mendeleev's periodic table contained a blank spot beneath iodine for a theoretical element named "eka-iodine." Scientists' subsequent attempts to find the element in nature were fruitless, and the quest to synthesize it in the lab was fraught with false starts. Fred Allison and his team at Alabama Technical Institute (now Auburn University) were the first in a series of researchers to mistakenly claim discovery of the elusive element in 1931; their discredited "alabamine" was followed by Rajendralal De's "dakin," Walter Minder's "helvetium," and Mitter and Alice Leigh-Smith's "anglo-helvetium." In 1940, Berkeley scientists Dale Corson, Kenneth Ross MacKenzie, and Emilio Segre were finally successful in artificially producing 211-At by bombarding a bismuth sputtering target with alpha particles in a particle accelerator. They named the element astatine from the Greek astatos, meaning "unstable." Astatine was the second synthetic element to be conclusively identified, technetium having been discovered by Segre and Carlo Perrier three years earlier.
Corson, MacKenzie, and Segre's method is still the primary means of synthesizing 209-211At; the bismuth target is first cooled under nitrogen and then heated to vaporize traces of other radioisotopes, allowing the astatine to be distilled and collected on a cold finger. Several compounds of astatine have been synthesized in microscopic amounts: in addition to hydrogen (hydrogen astatide, HAt, which forms hydroastatic acid when dissolved in water), astatine has been shown to bind to the other halides, silver, sodium, palladium, oxygen, sulfur, selenium, nitrogen, lead, boron, and tellurium, as a colloid. The first ionization energy of the astatine atom was unknown until 2013, when CERN scientists used laser spectroscopy to measure it as 9.31751 electron volts (eV), which was confirmed by Canada's national laboratory for particle and nuclear physics TRIUMF.
Astatine-211 is the element's only commercially viable isotope, its decay properties making it useful as a short-range radiation source for targeted alpha particle therapy in cancer treatment. Like iodine-113, it preferentially accumulates in the thyroid gland, but it decays faster and emits only alpha particles that have less of a tendency to migrate to surrounding tissue than the beta particles emitted by iodine-113.
Astatine: Astatine is almost non-existent on Earth and is found only in extremely minute quantities near uranium and thorium minerals.
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83. Tennessine - About Tennessine: Tennessine (Ts), previously referred to as eka-astatine and Ununseptium (Uus), is the designated name for element 117. The first reported successful synthesis of tennessine was achieved in 2010 by a collaboration between American and Russian teams. However, these experiments did not yield enough data to warrant an official claim of discovery to the IUPAC. In 2014, a team at the GSI research center in Germany claimed discovery, but the American and Russian collaboration was ultimately officially recognized as the discoverer of both elements 117 and 118. This team consisted of researchers from the Joint Institute of Nuclear Research in Dubna, Russia, the Research Institute for Advanced Reactors, Dimitrovgrad, and American teams from the Lawrence Livermore National Laboratory, Oak Ridge National Laboratory, Vanderbilt University in Tennessee, and the University of Nevada, Las Vegas. Their synthesis method involved bombarding a berkelium-coated titanium foil with calcium ions, triggering a fusion reaction of the calcium and berkelium isotopes to initiate a decay reaction.
As the official discoverers of two elements, the collaboration had the naming rights to both. Element 117 was named Tennessine in honor of the American half of the team, based on the location of Vanderbilt University. Element 118, previously known as Ununoctium, was named Oganesson in honor of the lead Russian scientist Yuri Oganessian. Although very few of its properties can be observed, Tennessine is expected to exhibit characteristics of the halogen group of elements based on its position on the periodic table.
Tennessine: Tennessine does not occur naturally and is not present in the earth's crust.
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84. Helium - About Helium: Helium (He), discovered in 1868 by French astronomer Jules Janssen during a solar eclipse, was named after Helios, the Greek god of the sun. This was fitting as it was the first element discovered in space before being found on earth. Scottish chemist William Ramsay successfully isolated the element in 1895 by treating a sample of the uranium ore cleveite, confirming its terrestrial existence.
On earth, helium is relatively scarce, produced only through the radioactive decay of elements such as uranium and thorium. It is the sixth most abundant gas in the atmosphere at 5.2ppm and one of the only elements light enough to possess escape velocity, rising and exiting the atmosphere at a rate roughly equal to its formation on earth. However, in space, helium is far more common; it is the second most abundant element in the universe after hydrogen, making up 24% of its total observable mass, and is primarily produced in the cores of hydrogen-burning stars that fuse protons into helium nuclei to produce light and heat.
Helium remained undetected by scientists for a long time due to its extreme chemical inertness, making it difficult to detect via conventional methods. This inertness is characteristic of the elements known as "noble gases" (Group 18 on the periodic table, which includes neon and argon), whose extreme stability and unwillingness to react with other elements is due to the completeness of their outer valence shells. Odorless, colorless, and nontoxic, helium is the lightest of the noble gases, and the second lightest of all elements in the universe after hydrogen. 99.999% of all helium atoms exists as stable isotope helium-4, composed of two protons, two neutrons, and two electrons in a single shell. This structure structure that yields the most stable and inert element on the periodic table, a monoatomic gas that always exists in pure elemental form in its natural state. Neon is the only element other than helium that has never been observed to bond with other elements in stable compounds; however, at temperatures close to absolute zero and under extreme pressure, helium can form unstable eximer molecules with elements like sodium, fluorine, and nitrogen. The helium-4 nucleus on its own is known as an alpha particle, the particle emitted in alpha-type radioactive decay. Approximate 0.0001% of natural helium is composed of its other stable isotope, helium-3, the nucleus of which has one neutron and is referred to as a helion. The existence of helium-3 was proven by Luis W. Alvarez and Robert Cornog at the Lawrence Berkeley National Laboratory in 1939. Seven other highly unstable isotopes are known; Helium-9, for example, has a half-life of 7 zeptoseconds, or seven sextillionths of a second.
Helium has the lowest solubility in water of any known gas and the lowest melting point of all elements on the periodic table; in fact, it is the only element that cannot be effectively solidified by merely lowering its temperature, as it remains liquid in form down to nearly absolute zero. Close to those temperatures, helium form a superfluid, a quantum state first discovered by Russian physicist Pyotr Kapitsa and John F. Allen in 1937: with almost zero viscosity or entropy, the fluid exhibits superconductivity and can flow up and over the walls of containers, defying the laws of gravity and surface tension, and can pass through nanoscale holes that would normally be impermeable to the gas. At 0.95K, helium can be transformed into a so-called supersolid or quantum solid by applying 25 atmospheres of pressure; to achieve the same result at room temperature requires 114,000 atmospheres of pressure, over 100 times greater than pressure experienced at the deepest point on the ocean floor. The unusual crystalline structure of solid helium exhibits an internal frictionless flow of atoms that impart properties like high compressibility and reversible plasticity.
Billions of cubic feet of helium are produced for commercial consumption each year, primarily from the natural gas wells between Amarillo, Texas and Hugoton, Kansas in the central United States. Helium comprises up to 7% of natural gas deposits and can be isolated from methane and other contaminants via the process of fractional distillation. Both liquid and gaseous helium play a role in the commercial sphere. Helium was first liquefied by Dutch physicist Heike Kamerlingh Onnes in 1913, earning him the Nobel Prize, and approximately 25% of helium's current commercial use is in liquid form for cryogenic refrigeration. Because helium remains in liquid form even at extremely low temperatures, it is used to cool superconducting wires in high-powered magnets used in magnetic resonance imaging (MRI) and large particle accelerators such as the Large Hadron Collider at CERN; it also serves as a heat-transfer medium for gas-cooled nuclear reactors thanks to its transparency to neutrons and high thermal conductivity. Buoyant in air, helium gas has had well-known use in ballooning since the early 20th century, eventually replacing hydrogen due to the latter's extreme flammability (as demonstrated by the infamous 1937 Hindenburg airship disaster). The first gas lasers employed a combination of helium and neon, and the air tanks of scuba divers substitute helium for nitrogen to prevent decompression sickness due to helium's lower blood solubility. Helium has applications in gas chromatography, industrial gas leak detection using helium mass spectrometers, and geological dating of thorium and uranium-containing rocks.
By far the most prominent commercial use for helium gas is providing an inert atmosphere for arc welding and semiconductor component fabrication, particularly during growth of high purity silicon and germanium single crystals. Other emerging roles in advanced technology for helium include allowing further investigation into the properties of quantum superfluids and supersolids, serving as a plasma source in plasma transistors that can operate at temperatures higher than silicon-based transistors, rocket propulsion from the fusion of helium-3 with deuterium, and using spin-polarized helium-3 beams for medical imaging and materials analysis.
Helium: Helium is found in the earth's crust and is also present in gases from certain mineral springs.
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85. Neon - About Neon: Neon, a noble gas, is the fifth most abundant element in the universe, following hydrogen, helium, oxygen, and carbon. However, its presence in Earth's atmosphere is quite rare, approximately 18 ppm. Neon's chemical inertness prevents it from forming neutral compounds, and thus, it cannot bind to solids. It is believed that neon's volatile nature, high vapor pressure, and relative lightness caused the element to escape in large quantities during Earth's formation under the sun's heat. Neon was discovered through the fractional distillation of liquefied air in 1898 by British chemists Sir William Ramsay and Morris Travers, just two weeks after they discovered another noble gas, krypton. Ramsay's method of isolating atmospheric elements was so successful that he was awarded the Nobel Prize for Chemistry in 1904.
Neon is a distinctive element that can only be produced through fractional distillation of liquefied air. Due to these factors, neon can be relatively expensive to produce and purchase. Its appealing characteristics in lighting applications are enabled by its activation (atom separation and recombination in a vacuum tube) at nominal voltages and currents in modern electrical systems. Neon itself emits a reddish-orange glow when activated, but lighting devices can replicate a range of colors in the visible spectrum when neon is mixed with other gases. This property led neon to be the precursor of today's modern plasma displays and TV screens. Lesser-known applications include neon as a refrigerant in its liquid form, boasting 40 times the refrigerant capacity of liquid helium and three times that of liquid hydrogen.
Neon has three stable isotopes: 20Ne, 21Ne, and 22Ne. Both 21Ne and 22Ne are primordial (have existed since Earth's formation) and nucleogenic (produced through naturally occurring nuclear reactions). The nucleogenic instances of neon isotopes are known to result from nuclear reactions, primarily with 24Mg and 25Mg. 20Ne, on the other hand, is known to be primordial but not nucleogenic. The relative sources of 20Ne, the most abundant of the three isotopes on Earth, are still debated today. Due to the enriched amounts of 20Ne in volcanic gas and its presence in diamonds, some theorize that a "solar neon reservoir" may exist within the Earth. Through the scientific discovery and analysis process of all three naturally occurring neon isotopes, it is now theorized that neon can be useful in determining cosmic exposure ages of meteorites and rocks located on a planetary body's surface.
Neon: Neon is mostly obtained from liquefying air. There are no neon-bearing minerals.
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86. Argon - About Argon: Argon, the third most abundant gas in Earth's atmosphere after nitrogen and oxygen, is a noble gas produced through the fractional distillation of liquefied air. Its inert nature and relative abundance compared to other noble gases have led to its wide use in various applications. Annually, approximately 700,000 tons of argon are produced for use in industrial applications and consumer products.
In lighting applications, both incandescent and fluorescent, argon is used to prevent the bulb's filament from corroding due to oxygen. Its inert nature also makes it suitable for use in many industrial applications that require an atmospheric barrier or shielding gas between a high-temperature source and the normal composition of air. This is evident in its use in arc welding and graphite electric furnaces.
Argon's versatility extends to more exotic applications as well. Scientists liquefy argon to observe neutrinos and search for dark matter. It also serves as a preservative for food and historical documents, a humane method for euthanizing diseased animals, a fire extinguisher, and a medical tool in laser apparatuses for correcting eye defects and welding arteries.
Argon holds the distinction of being the first noble gas discovered. In 1894, Sir William Ramsay of England and Lord Rayleigh of Scotland found that the nitrogen resulting from an air sample, from which oxygen, carbon dioxide, and all moisture had been removed, was heavier than the nitrogen produced from reducing chemical compounds. This led them to believe that another element was present in the resulting nitrogen sample. After several months of isolating nitrogen from the other components of air, they discovered argon. For their discovery and Rayleigh's persistence, Rayleigh was awarded the Nobel Prize in Physics in 1904.
Argon is a stable and largely inert element that has yet to form any known compound at room temperature. Only one compound, HArF, has been produced at very low temperatures, but it has no practical application outside of fundamental scientific research. Argon has three naturally occurring isotopes: 36Ar, 38Ar, and 40Ar, with 40Ar being the most abundant on Earth. 40Ar is produced through the slow decay of 40K in rocks at the Earth's crust over long periods of time. The relative abundance of these three isotopes is inverted in the atmospheres of outer planets within the solar system, where the production of argon is dominated by stellar nucleosynthesis, and the decomposition of rocks is naturally far less abundant.
Argon: Argon is obtained from liquefying air. There are no argon-bearing minerals.
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87. Krypton - About Krypton: Krypton, a noble gas with the atomic number 36, is found in trace amounts (1 ppm) in the Earth's atmosphere. The isolation of this element through the fractional distillation of liquefied air is costly, limiting its widespread use in practical applications. However, when isolated, krypton finds commercial use in high-speed photographic flash bulbs and, when mixed with other gases like argon, in fluorescent lamps.
Despite being mostly inert, a few compounds containing krypton are known to exist. Krypton difluoride (KrF2), a volatile and colorless solid, is one such compound, typically produced in gram quantities.
The combination of krypton with fluorine opens up a range of industrial and scientific applications. Krypton fluoride lasers, which produce a deep-ultraviolet beam, are extensively used in photolithography during the manufacturing process of semiconductor integrated circuits. The short wavelength of its emitted light (y = 248 nm) has significantly reduced piece-part spacing in microelectronic chips throughout the 1990s and 2000s. This has increased the density of piece-parts on a microchip, such as transistors in a CPU, thereby increasing switching speed and lowering the cost of manufacturing electronic devices. As such, the krypton fluoride laser has been recognized as a key contributor in maintaining Moore's Law during this period.
Krypton was discovered in 1898 by Sir William Ramsay, a chemist and the recipient of the 1904 Nobel Prize in Chemistry for his isolation of noble gases, and Morris Travers. They discovered krypton by evaporating components of liquefied air. Since then, six naturally occurring, stable isotopes of krypton have been discovered. One of these isotopes, 81Kr, has proven useful in dating groundwater. 85Kr, a byproduct of uranium or plutonium fission, is radioactive with a half-life of 10.76 years. 86Kr, characterized by the 605nm wavelength of its orange-red spectral line, was declared the official internationally-accepted definition of 'meter' as a unit of measure in 1960, replacing a metal bar. However, it was itself replaced in 1983 by the distance that light travels in a vacuum.
Krypton: Krypton is obtained from liquefying air. There are no krypton-bearing minerals.
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88. Xenon - About Xenon: Xenon, a rare noble gas with an estimated abundance of 0.1 ppm in Earth's atmosphere, was one of the last gases to be isolated. This isolation was achieved by Sir William Ramsay and Morris Travers in 1898 through their research on the fractional distillation of liquefied air. To date, xenon is produced only via this method, albeit with increased efficiency over the decades.
Long considered to be completely inactive, xenon became the first noble gas to be synthesized into a chemical compound, bonding with a form of platinum fluoride to form xenon hexafluoroplatinate. Since the 1960s, scientific research has yielded several other exotic compounds, although none have yet found applications outside of scientific circles.
Like other noble gases such as helium, xenon's primary application is in lighting. It produces an extremely bright bluish-white light, making it useful in photographic flashes and lighting equipment. Strobe lights contain xenon for this reason. The strength of the light emitted by xenon also makes this element useful in lasers and bacteria-killing ultraviolet light sources used to sterilize lab equipment. In the medical industry, xenon is used as a general anesthetic, and several of its isotopes are utilized in the study of blood flow through the brain and lungs. Xenon is even used in ion thrusters for deep-space spacecraft. The observation of xenon content is also useful in dating events in the early solar system.
Xenon has eight stable isotopes, the most of any element next to tin, and over 40 known unstable isotopes, some of which are radioactive. 135Xe is often used as a neutron absorber that can slow or stop nuclear reactions. The Chernobyl disaster taught the scientific community that powering down a reactor without accounting for the ensuing buildup of xenon can further poison the whole reactor. Along with 133Xe, 135Xe is also used as an observable barometer to monitor compliance with nuclear test ban treaties or to confirm that a nuclear detonation has taken place. Liquid xenon is used in calorimeters for measurements of gamma rays and as a medium to detect weakly interacting massive particles.
Xenon: Xenon is obtained from liquefying air. There are no xenon-bearing minerals.
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89. Radon - About Radon: Radon is a naturally occurring radioactive noble gas, derived from the decay of uranium and thorium deposits. The discovery of this element is attributed to various scientists, including Pierre and Marie Curie in 1899, Friedrich Ernst Dorn in 1900, Ernest Rutherford in 1901, and Andre-Louis Debierne in 1903. Each of these scientists observed that gases emitted by different radioactive elements remained active for some time. It was later recognized that these gases were different isotopes of a single new element in the noble gas family.
This new element was extensively characterized by Sir William Ramsay and Robert Whytlaw-Gray in 1910. It was subsequently named "radon," with isotope numbers replacing the separate names initially given to each isotope. Until the 1960s, the radioactive gas was often referred to as an "emanation" from a specific radioactive element.
Radon's radioactivity and its presence in natural deposits make it a significant health hazard, contributing to lung cancer in those exposed. Exposure typically occurs due to underground leaks, with both radon gas and small particles of its solid decay products potentially being inhaled, leading to radiation exposure in lung tissue. Radon's primary application is in cancer treatment, where it is sealed into tiny metal seeds that are implanted into tumors for continuous radiotherapy. It is also sometimes used as a radioactive tracer to check structures for gas leaks.
Radon: Radon comes from the natural decay of uranium or thorium, elements found in rocks, soils, and water.
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90. Oganesson - About Oganesson: Oganesson (Og), previously referred to as Ununoctium (Uuo), is a transactinide element with the atomic number 118. The International Union of Pure and Applied Chemistry (IUPAC) officially recognized the discovery of this element in 2015, crediting a collaborative team of Russian and American researchers. This team included scientists from the Joint Institute of Nuclear Research in Dubna, Russia, the Research Institute for Advanced Reactors in Dimitrovgrad, and American teams from the Lawrence Livermore National Laboratory, Oak Ridge National Laboratory, Vanderbilt University in Tennessee, and the University of Nevada, Las Vegas. The synthesis of Oganesson involved a collision of californium and calcium ions, triggering a decay reaction that resulted in the formation of 294Uuo.
The collaborative team, as the official discoverers of elements 117 and 118, were granted the privilege of naming both elements. Element 117 was named Tennessine, honoring the American half of the team and the location of Vanderbilt University. Element 118 was named Oganesson in tribute to the leading Russian scientist, Yuri Oganessian. Although only a few of its properties can be observed, Oganesson is anticipated to display characteristics of the noble gas group of elements, based on its position on the periodic table.
Oganesson: Oganesson does not occur naturally. The only source of the element is a nuclear research laboratory.
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91. Cerium - About Cerium: Cerium, discovered in 1803 by Jons Jacob Berzelius, is named after the dwarf planet Ceres. As the most abundant of the rare earth elements, it was initially identified in the form of its oxide, ceria, and wasn't obtained as a pure metal until several decades post-discovery. Despite this, cerium salts and metallic mixtures found immediate industrial applications. Cerium salts, known for their anti-emetic properties, were incorporated into cough tinctures and antibacterial treatments. Concurrently, Austrian scientist Carl Auer von Welsbach developed two cerium-requiring products: gas mantles and lighter flints. Auer's gas mantles, simple cotton fabric soaked in salt mixtures, emitted a bright, white light when heated, enhancing the illumination provided by gas lamps. Cerium also found application in carbon-arc lamps, prized in film studios for their extreme brightness and ability to simulate natural sunlight.
While cerium compounds have limited use in modern medicine, with the exception of cerium nitrate used as an antiseptic and anti-inflammatory topical treatment for burns, cerium's use in lighting has persisted and evolved. Cerium-containing lantern mantles and cerium alloy lighter flints remain in production, and cerium-containing phosphors are now crucial in the manufacture of display screens and fluorescent lamps.
Cerium's optical properties render it a key component of nontoxic alternatives to cadmium-based pigments and a valuable additive in glass manufacturing, where it imparts a golden color and facilitates selective UV light blocking. When added in small quantities to various alloys, cerium enhances aluminum's corrosion resistance, increases magnesium's heat resistance, and aids in reducing the sulfur and oxygen content of steel. The most voluminous use of cerium is as the polishing agent cerium (IV) oxide, used on precision optical components and for polishing silicon wafers in microchips. Cerium oxides also serve as catalysts in motor vehicle catalytic converters, petroleum refining, and solid oxide fuel cells.
Cerium, like other rare earth elements, is never found in its pure form in nature. It can only be obtained from rare earth-containing minerals such as xenotime, monazite, and bastnasite, or from ion-adsorption clays.
Cerium: Cerium is obtained from cerium-rich monazite and bastnasite. It is also found in allanite.
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92. Praseodymium - About Praseodymium: Praseodymium, a rare earth element, was first believed to be an oxide of a new element called didymium, as discovered by Carl Gustav Mosander in 1841. However, later experiments by Austrian chemist Carl Auer Welsbach in 1885 revealed that this oxide was a mixture of salts of two new elements, praseodymium and neodymium. The yellow-green solution of praseodymium salts led to its naming from the Greek words 'prasinos' (green) and 'didymos' (twin).
Praseodymium, like many rare earth elements, is primarily used in small amounts to "dope" other materials, imparting useful properties even in minor concentrations. It is often used to modify optical properties or in light production or detection applications. Praseodymium is found in didymium glass used in safety goggles that block harmful intense ultraviolet, infrared, and yellow light during certain types of welding and glassworking. Praseodymium-doped fluoride glass serves as a fiber optical amplifier for light around a wavelength of 1300nm. Praseodymium-doped crystals are used as gain media in solid-state lasers. Praseodymium compounds can yield either a yellow or yellow-green coloring, depending on the application; in glass and enamel, praseodymium is used for yellow coloring. Adding praseodymium to cubic zirconia produces a yellow-green stone that mimics the mineral peridot. Modern medical computed tomography (CT) scanners often use praseodymium-doped scintillator crystals in their X-ray detecting sensors.
Furthermore, praseodymium is used as a dopant in alloying applications, catalysts, and other novel materials. Small amounts of praseodymium alloyed with magnesium produce high-strength metals used in demanding applications such as jet engines. Praseodymium-nickel alloys exhibit an extremely strong magnetocaloric effect and have been used in refrigeration devices to attain extremely low temperatures. Praseodymium is used in small amounts in neodymium magnets, which are the strongest permanent magnets commercially available. Praseodymium-doped ceria can be used to catalyze a variety of reactions. Praseodymium-doped thin films are being investigated due to a variety of potentially useful properties including photoluminescence. Praseodymium-doped yttrium silicate crystals are used in quantum computing research.
Praseodymium nickelates, praseodymium-doped ceria, and praseodymium barium copper oxide are all being researched as cathode materials for solid oxide fuel cells. Historically, the rare-earth alloy mischmetal was used in lighter flints, and modern flints still contain small amounts of praseodymium along with other rare earths. Finally, praseodymium oxide thin-film surface coatings provide antireflective properties and durability.
Praseodymium, one of the light rare earths, is typically sourced from the minerals monazite and bastnasite, along with other elements from that group.
Praseodymium: Praseodymium is chiefly obtained from monazite and bastnasite.
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93. Neodymium - About Neodymium: Neodymium, a rare earth element, was initially believed to be an oxide of a new element named didymium, as discovered by Carl Gustav Mosander in 1841. The name 'didymium' was derived from the Greek word 'didymos', meaning twin, due to its perceived similarity to lanthanum, another rare earth element previously discovered by Mosander. Didymium was even included in an early version of Dmitri Mendeleev's periodic table. However, later experiments by Austrian chemist Carl Auer Welsbach in 1885 revealed that Mosander's oxide was actually a mixture of salts of two new elements, praseodymium and neodymium. The term 'dymium' was retained from the original name, and 'neo' was added, which simply means 'new'.
Neodymium magnets, composed of an alloy of neodymium, iron, and boron, are the strongest known permanent magnets. They play a crucial role in many modern electronics, including microphones, speakers, hard disks, and electric motors. The majority of neodymium's commercial use is in the production of these high-strength magnets.
In most other applications, neodymium is added in small amounts to modify the properties of a host material. Neodymium oxide is used as a colorant to produce glass that changes shade depending on the type of lighting it is viewed under, a property cherished by collectors. This color change phenomenon results from the sharp absorption bands of light transmitted through neodymium glasses, making the same glass useful for photography filters and in scientific settings. Additionally, neodymium, in combination with praseodymium, is used to produce glass for safety goggles that block the high-intensity yellow light and ultraviolet and infrared light produced during welding or glass blowing. Neodymium is also a vital component of various gain media used in lasers operating at infrared wavelengths. Yttrium aluminum garnet, yttrium lithium fluoride, and yttrium orthovanadate crystals can all be doped with neodymium for this purpose. Commercially available laser pointers generally use neodymium-doped crystals to produce infrared light that is converted to green light. Furthermore, neodymium glass can itself be a laser gain medium and is particularly useful in extremely high-power lasers.
Neodymium, one of the light rare earths, is typically sourced from the minerals monazite and bastnasite, along with other elements from that group.
Neodymium: Neodymium is chiefly obtained from monazite and bastnasite.
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94. Promethium - About Promethium: Promethium, a rare earth element with all isotopes being radioactive and having short half-lives, is not found in significant amounts in natural sources. The existence of this elusive element, bearing the atomic number 61, was predicted by Henry Mosley in 1914. However, it wasn't until 1945 that the element was successfully produced and fully characterized. This feat was achieved by Jacob A. Marinsky, Lawrence E. Glendenin, and Charles D. Coryell at Oak Ridge National Laboratory, who separated and analyzed the fission products of uranium.
The element was named after Prometheus, the Titan in Greek mythology who stole fire from Mount Olympus to give to humans. This name is fitting, as promethium can only be obtained through human ingenuity in a laboratory setting, much like how fire was brought to mankind in the myth.
Promethium has limited applications due to its scarcity and radioactivity. The only isotope of promethium used outside of research is promethium-147. This isotope is produced and used in minuscule quantities (milligrams) in atomic batteries and signal lights. These devices contain phosphors that emit light in response to the absorption of radiation emitted by the isotope. Given that this relatively stable isotope emits x-rays, it holds theoretical potential for use in portable x-ray sources.
Promethium: Promethium does not occur naturally. It is believed to be present in trace quantities in uranium minerals, as it is part of uranium's radioactive decay series.
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95. Samarium - About Samarium: Samarium, a rare earth element, was first discovered in 1839 by German mineralogist Gustav Rose. He identified a new mineral in samples provided by Russian mining engineer Samarsky-Bykhovets, which was eventually named samskarite in his honor. In 1879, French chemist Paul Emile Lecoq de Boisbaudran isolated an oxide of a new element from this mineral and named it samarium, making it the first chemical element to be named, albeit indirectly, after an individual.
The pure metal was not easily obtainable in commercial quantities until the 1950s. However, a byproduct of the purification of other rare earths with a high percentage of samarium found early use in control rods for some of the first nuclear reactors.
Today, samarium has numerous applications. Its most significant use is in high-strength samarium-cobalt magnets, which are slightly less strong than neodymium magnets but are preferred in some applications due to their ability to maintain their magnetic properties at significantly higher temperatures. These magnets are commonly found in small motors, speakers, and other electronic devices.
Samarium also plays a significant role in catalysis. Samarium catalysts are used in various industrial processes, including the decomposition of plastics, dechlorination of pollutants, and dehydration of ethanol. Additionally, a variety of samarium compounds are used as catalysts and reagents in organic synthesis.
Samarium can also be used to provide useful properties to a substrate material such as glass when added in small quantities during production, a process often referred to as doping. Samarium oxide is added to ceramics and glasses to increase absorption of infrared light. Samarium-doped crystals have been used as gain media for lasers since one of the first solid-state lasers was produced by IBM research labs in 1961.
Several specific isotopes of samarium have specialized uses. The radioactive isotope samarium-153 is used in the treatment of some advanced cancers, as it naturally localizes to the bones and emits beta particles that kill the nearby cancer cells, lessening the extreme pain of bone metastases. Samarium-149 is notable for being an excellent absorber of neutrons and is used in this capacity in the control rods of nuclear reactors.
Finally, there are a number of samarium applications still under development. A group of compounds called samarium monochalcogenides are crystalline semiconducting solids with interesting properties. In particular, the electrical properties of the solids change depending on the pressure applied to the material, and the material generates electric voltage when heated. These unique phenomena are being investigated for use in pressure sensors, memory devices, and thermoelectric power converters. Samarium can be used in the production of superconducting materials, and samarium-doped iron superconductors are among the highest-temperature superconductors known. Samarium-doped cerium oxide nanostructures are of interest for use in solid oxide fuel cells.
Samarium is a rare earth element and is found along with other elements of this group in a variety of rare earth minerals. The primary commercial sources are the minerals monazite and bastnasite.
Samarium: Samarium is obtained from bastnasite and monazite. It is also found in samarskite, cerite, orthite, ytterbite, and fluorspar.
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96. Europium - About Europium: Europium, a rare earth element, was discovered in 1901 by Eugene-Anatole Demarcay. He found that the samples of samarium and gadolinium he had obtained five years earlier contained impurities of an unknown element. Breaking away from the trend of naming newly discovered elements after countries, Demarcay named his discovery after the entire continent of Europe. Interestingly, when the Euro was introduced nearly a century later, phosphorescent europium compounds were aptly chosen for anti-counterfeiting measures in the currency notes.
Europium is primarily used in light-emitting compounds known as phosphors, which are found in many places, including Euro notes. The advent of a europium-containing red phosphor revolutionized color television technology in the 1960s. Before the introduction of europium phosphors, the phosphors used to produce the color red in color televisions were quite weak. To maintain color balance, all other colors had to be subdued. The introduction of brighter red phosphors led to the possibility of brighter color televisions.
Today, two different classes of europium oxide phosphors emit red and blue light. These can be used separately or combined with a yellow-green phosphor to produce white light. Europium phosphors are used in televisions, fluorescent lighting, and some LEDs. Additionally, europium is used as a dopant in glasses for lasers and other optoelectronic applications, and it has some specialized research applications.
Europium, being a rare earth element, can be found in varying quantities in most minerals that contain rare earth elements. It is most commonly extracted from the minerals monazite and bastnasite.
Europium: Europium is obtained from bastnasite and monazite. It is also found in xenotime and loparite-(Ce).
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97. Gadolinium - About Gadolinium: Gadolinium, a rare earth element, was discovered by Swiss chemist Jean Charles Galissard de Marignac in 1880. He found an oxide of an unknown element in a sample of gadolinite, a mineral named after Finnish chemist and geologist Johan Gadolin, who discovered the first rare earth element, yttrium, in 1794. Gadolinium, named from its oxide, was the second element to be named after an individual, following samarium.
Gadolinium is known for its unique magnetic properties. It is ferromagnetic below 20 degrees Celsius and paramagnetic above this temperature. Gadolinium compounds are used in magnetic resonance imaging (MRI) scanning to enhance contrast between normal and healthy tissue. Gadolinium also exhibits the magnetocaloric effect, which is exploited in magnetic refrigeration devices.
Another notable property of gadolinium is its high adsorption rate of neutrons. In nuclear energy applications, gadolinium is used in radiation shielding and to control the rate of the nuclear reaction. Gadolinium may also be used in neutron radiography, an imaging technology that uses neutrons, similar to how x-rays are used in x-ray imaging.
Gadolinium can be used to produce compounds that exhibit luminescence, either in response to the absorption of visible or near-visible light (phosphors) or in response to the absorption of ionizing radiation (scintillators). Gadolinium phosphors are used for green light in color display screens, while scintillator compounds containing gadolinium are used in sensors that detect X-rays or neutrons.
Gadolinium-153, a radioactive isotope, is used in testing and calibration of medical imaging devices, bone density measurements, and in Lixiscope portable x-ray systems. It has also been investigated for potential use in radiotherapy for cancer.
In some contexts, gadolinium is used in small quantities to alter the properties of a host material. In metallic alloys, gadolinium improves the workability of the material and increases resistance to high temperatures and oxidation. Gadolinium-doped garnets have applications in magneto-optical devices, lasers, and as imitation gemstones. Gadolinium-doped ceria is a potential electrolyte material for fuel cells.
Several gadolinium compounds have been investigated for use as superconductors. Other uses currently in development for gadolinium include luminescent oxygen and temperature sensing compounds, novel high-k dielectrics for semiconductor devices, high temperature piezoelectric compounds for pressure and force detecting sensors, and compounds which can be used to immobilize and contain radioactive waste.
Gadolinium, being a rare earth element, can be found in varying quantities in most minerals that contain rare earth elements. It is most commonly extracted from the minerals monazite and bastnasite.
Gadolinium: Gadolinium is chiefly obtained from bastnasite and monazite. It also occurs in the mineral gadolinite.
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98. Terbium - About Terbium: Terbium, a rare earth element, was discovered by Carl Axel Arrhenius, an army lieutenant and chemist, in 1787. He found a rock in a quarry near the Swedish village of Ytterby, which he suspected contained the newly discovered element tungsten. Although his suspicions were not confirmed, four new elements were eventually identified from Arrhenius's ytterbite. In 1843, Carl Gustaf Mosander isolated three new oxides, one of which he named terbia, leading to the naming of the corresponding element, terbium.
Terbium-doped compounds can serve as phosphors in television screens, other displays, lighting, or sensors. Notably, terbium green phosphors are used in trichromatic fluorescent lamps, along with europium blue and red phosphors, to produce white light with greater energy efficiency than incandescent lighting. In zirconia oxide ceramics, terbium can act as both a light-emitting dopant and a crystal stabilizer, producing a material with excellent structural and optical properties. Other terbium-doped compounds have useful electrical properties that make them potentially useful in the semiconductor industry.
Terfenol-D, an alloy of terbium, iron, and dysprosium, is magnetostrictive, meaning it contracts or expands when exposed to magnetic fields. This property allows for direct conversion between electrical and mechanical power, and the alloy is used in sensors, actuators, acoustic and ultrasonic transducers, and active noise and vibration canceling devices. Terbium was also a component of gadolinium-terbium-iron thin films used in magneto-optical memory storage devices and specialized compact discs (CD-MO), but other forms of computer memory are currently preferred for most applications. Additionally, engineered terbium-binding peptides are being developed for use as sensitive optical biosensors for sensing enzymatic activity, and several radioactive terbium isotopes are being developed for medical applications as diagnostic tracers or cancer treatments.
Terbium, being a rare earth element, can be found in any mineral that contains rare earth elements. However, as a heavy rare earth element (HREE), it is more common in HREE-enriched minerals such as xenotime and euxenite. Additionally, terbium is present in ion adsorption clays, which are a major source of HREEs due to their relative ease of processing, despite the low percentage quantities of rare earths they contain.
Terbium: Terbium is chiefly obtained from monazite. It also occurs in cerite, xenotime and gadolinite.
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99. Dysprosium - About Dysprosium: Dysprosium, a rare earth element, was discovered by French chemist Paul Emile Lecoq de Boisbaudran in 1886. He isolated dysprosium oxide from an impure sample of holmium oxide. The process of deriving the metal from the oxide was challenging, leading to the element being named from the Greek word dysprositos, meaning "hard to get". It wasn't until the 1950s, with the development of ion exchange techniques, that significant pure quantities of many rare earth elements, including dysprosium, could be obtained.
Dysprosium and its compounds have unique properties that make them useful in a variety of applications. Compounds containing dysprosium can emit light under certain conditions. For instance, dysprosium-doped calcium sulfate or calcium fluoride crystals luminesce when exposed to radiation, making them useful in dosimeters for measuring radiation exposure. Dysprosium iodide and bromide are used in metal-halide lamps, which produce extremely bright white light, a feature valued in the film industry. Furthermore, dysprosium compounds can produce infrared light and are often used in infrared lasers.
The magnetic properties of dysprosium and its compounds are also highly valued. Easily magnetized dysprosium compounds can be used in data storage applications such as hard drives. Dysprosium is often used to substitute for some of the neodymium in neodymium-iron-boron magnets, increasing their corrosion resistance and coercivity. These high-powered magnets are essential for electric motors, magnetic memory devices such as hard drives, and many other modern electronics. Dysprosium-containing garnets with magnetic properties are used in magnetic refrigeration devices, which can reach extremely low temperatures. Terfenol-D, an alloy of terbium, iron, and dysprosium, is magnetostrictive, meaning it contracts or expands when exposed to magnetic fields. This property allows for direct conversion between electrical and mechanical power, and the alloy is used in sensors, actuators, acoustic and ultrasonic transducers, and active noise and vibration canceling devices.
Dysprosium's ability to absorb neutrons effectively makes it useful in nuclear reactor control rods. It can also be used to produce nanofibers that are high-strength and naturally corrosion-resistant, potentially serving as reinforcement in ceramic materials designed for high-temperature applications.
Like other rare earth elements, dysprosium is never found in its pure form in nature. It can only be obtained from rare earth containing minerals such as xenotime, monazite, and bastnasite, or from ion-adsorption clays.
Dysprosium: It is chiefly obtained from bastnasite and monazite, where it occurs as an impurity. Other dysprosium-bearing minerals include euxenite, fergusonite, gadolinite, and polycrase.
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100. Holmium - About Holmium: Holmium, a rare earth element, was discovered in 1878 when Marc Delafontain and Jacques-Louis Soret identified spectroscopic absorption bands of an unknown element. Later that year, Per Teodor Cleve isolated the oxide of this element. All three scientists are credited with the discovery of this new element, which was named holmium, after Stockholm, the hometown of Cleve.
Holmium boasts the highest magnetic strength of any element, making it invaluable in the creation of extremely potent magnetic fields as a magnetic flux concentrator within high-strength magnets. Due to its rarity, holmium is typically used as a component in magnets rather than for the fabrication of complete magnets.
In addition to its magnetic properties, holmium serves as a dopant in garnets, cubic zirconia, and glass. Holmium-doped garnets are utilized in solid-state lasers that emit at wavelengths safe for medical and dental applications, and they are also employed in fiber optic communication devices. In glass and cubic zirconia, holmium imparts a yellow or red color and exhibits distinctive absorption peaks, making these materials useful as calibration standards for optical spectrophotometers. The radioactive isotope holmium-166m1 is also used for calibrating gamma ray spectrometers.
As a rare earth element, holmium can be found in any mineral containing rare earth elements. However, as a heavy rare earth element (HREE), it is more commonly found in HREE-enriched minerals such as xenotime and euxenite. Holmium is also present in ion adsorption clays, which, despite containing low percentage quantities of rare earths, serve as a major source of HREEs due to their relative ease of processing.
Holmium: Holmium occurs in gadolinite, monazite, and in other rare earth minerals.
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101. Erbium - About Erbium, a rare earth element, was discovered in 1787 by Carl Axel Arrhenius, an army lieutenant and chemist. He found a rock in a quarry near Ytterby, a Swedish village, which he believed contained the newly discovered element tungsten. Although other chemists' analyses did not confirm his suspicions, four new elements were eventually identified from the mineral that Arrhenius had named "ytterbite" in honor of Ytterby. In 1843, Carl Gustaf Mosander isolated three new oxides, one of which he named erbia, leading to the naming of the element erbium.
Erbium 3+ ions possess optical properties that are responsible for most of the element's applications. Erbium-doped glasses and crystals are used as laser gain media, optical fibers, and amplifiers in fiber optic communication systems. Erbium lasers are commonly used in medical, dermatological, and dental settings, and more powerful erbium-ytterbium lasers are used in metal cutting and welding. The unique absorption and emission spectra of erbium make it useful for functional optical applications and give erbium 3+ compounds a distinct pink color. As a result, erbium is also used as a colorant for glasses, ceramics, and cubic zirconia.
In addition to its optical properties, erbium is valued for its ability to absorb free neutrons readily, making it useful in control rods in nuclear reactors. Furthermore, erbium alloys, due to their high specific heat capacity, are used in cryocoolers for use near liquid helium temperatures.
As a rare earth element, erbium can be found in any mineral containing rare earth elements. However, as a heavy rare earth element (HREE), it is more commonly found in HREE-enriched minerals such as xenotime and euxenite. Erbium is also present in ion adsorption clays, which, despite containing low percentage quantities of rare earths, are a significant source of HREEs due to their relative ease of processing.
Erbium: Erbium is obtained from bastnasite and monazite, where it occurs as an impurity.
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102. Thulium - About Thulium: Thulium, a rare earth element, was discovered in 1879 by Per Teodor Cleve, a Swedish chemist. While examining samples of rare earth oxides for impurities, he isolated two new oxides, leading to the identification and naming of the elements holmium and thulium. The name thulium is derived from Thule, an ancient name for Scandinavia.
Despite its rarity and high cost, thulium has a variety of commercial applications. It is notably used as a dopant for garnets that serve as laser gain media. These lasers are utilized in medical applications such as laser surgery, as well as in industrial and military applications. The radioactive isotope thulium-170, which can be produced in nuclear reactors, is found in portable x-ray devices used for medical diagnostics and manufacturing quality control. This isotope can also be used in radiotherapy for cancer treatment.
Thulium has other specialized uses that are either currently in use or under development. For instance, it may be used in high-temperature superconductors, magnetic ceramic materials, personal radiation dosimeters, and phosphors used in anti-counterfeiting features of modern currency notes.
As a rare earth element, thulium can theoretically be found in any mineral containing rare earth elements. However, as a heavy rare earth element (HREE), it is more commonly found in HREE-enriched minerals such as xenotime and euxenite. Thulium is also present in ion adsorption clays, which are a significant source of HREEs due to their relative ease of processing, despite their low percentage quantities of rare earths. In any source of rare earths, thulium constitutes an extremely small percentage of the total rare earth content, making it one of the rarest of the rare earth elements.
Thulium: Thulium is chiefly obtained from bastnasite and monazite, where it occurs as an impurity.
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103. Ytterbium - About Ytterbium: Ytterbium, a rare earth element, was first identified in 1878 by Swiss chemist Jean Charles Galissard de Marignac. He isolated ytterbium oxide from a sample of gadolinite, suspecting the compound contained an unknown element. The element was named "ytterbium" after the Ytterby mine in Sweden, where the initial gadolinite samples were found. Ytterbium is the last of four elements named in association with this mine, the others being yttrium, terbium, and erbium.
Ytterbium is primarily used as a dopant. In crystal and glass structures, ytterbium doping results in the production of laser media and optical fibers. When added to stainless steel, ytterbium enhances grain refinement and strength. It can also be added to silicon photocells to improve the efficiency of solar energy absorption at infrared wavelengths. Furthermore, ytterbium is used in thermal barrier coatings on transition metal alloy substrates.
One unique property of ytterbium metal is its increase in electrical resistance when under stress. This property is exploited in stress gauges used to monitor ground deformations from earthquakes and nuclear explosions. Ytterbium has also been used to create an atomic clock with greater accuracy than the current time standard, the cesium atomic clock. Experimentally, ytterbium is being investigated for various specialized applications, including highly sensitive small-molecule sensors and medical X-ray computed tomography scan contrast agents.
As a rare earth element, ytterbium can theoretically be found in any mineral containing rare earth elements. However, as a heavy rare earth element (HREE), it is more commonly found in HREE-enriched minerals such as xenotime and euxenite. Ytterbium is also present in ion adsorption clays, a significant source of HREEs due to their relative ease of processing, despite their low percentage quantities of rare earths.
Ytterbium: Ytterbium is chiefly obtained from the minerals euxenite and xenotime.
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104. Lutetium - About Lutetium: Lutetium, a rare earth element, was independently identified by several chemists in 1907, including Georges Urbain in France, Carl Auer von Welsbach in Austria, and Charles James in America. They were all working with an impure sample of ytterbium oxide. The name "lutetium," proposed by Urbain, was derived from the Greek name for Paris and was ultimately accepted as the official name for the element.
Despite its rarity, lutetium has several commercial applications. It is used as a dopant in garnets for specialty lenses and magneto-optical memory storage devices. Cerium-doped lutetium oxyorthosilicate (LSO) is one of the most effective materials for detectors in positron emission tomography (PET) scanners. Lutetium can also be used in small quantities as a catalyst in petroleum cracking and other industrial chemistry applications. Lutetium tantalate, the densest known stable white material, can be used as a host material for X-ray phosphors. Furthermore, lutetium can serve as a dopant in various phosphors and scintillator crystals. Radioactive isotopes of lutetium are used in radioactive dating and experimental cancer therapies.
As a rare earth element, lutetium can theoretically be found in any mineral containing rare earth elements. However, as a heavy rare earth element (HREE), it is more commonly found in HREE-enriched minerals such as xenotime and euxenite. Lutetium is also present in ion adsorption clays, a significant source of HREEs due to their relative ease of processing, despite their low percentage quantities of rare earths.
Lutetium: Lutetium is obtained from the minerals bastnasite and monazite, where it occurs as an impurity.
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105. Thorium - About Thorium: Thorium, a radioactive element in the actinide family, is a soft silvery-white metal in its pure form. It shares similar properties with lead and can be easily shaped under the right conditions. Thorium is relatively abundant in the earth's crust (15 ppm), making it more common than other radioactive elements, especially uranium. This abundance positions thorium as a potential candidate for reducing the cost of future nuclear power sources.
Thorium is typically extracted by converting a sample of monazite or thorite to thorium dioxide and then heating the compound with calcium. This process can transform thorium into various synthetic isotopes of uranium through neutron bombardment, if desired (e.g., for breeder reactors). However, only one thorium nuclear reactor was ever built (in 1979), and it was shut down after a decade due to numerous economic and technical issues.
Thorium's inherent characteristics make it suitable for a range of industrial and consumer applications. In fact, thorium is the only radioactive element, besides uranium, with non-radioactive applications. Its ability to maintain strength at high temperatures is central to these applications. Thorium is used in some magnesium alloys for aircraft engines and rockets, and oxidized thorium is used in arc welders. Compounds like thorium dioxide and thorium nitrate serve as brilliant white light sources when heated with a gas flame, finding use in various lights and lamps. Thoriated tungsten elements are found in magnetrons, commonly used in microwave ovens and radar systems. Moreover, thorium dioxide is used in many ceramics and glasswork applications, including optical lenses for cameras and scientific apparatuses, due to its ability to increase the refractive index in glass. Thorium fluoride is used as an optical coating. Despite the safety of small amounts of thorium in such applications, thorium-based products have started to lose favor since the 2000s due to perceived biological risks.
Thorium was discovered in 1828 by Swedish chemist Jons Jakob Berzelius, before the concept of radioactivity was known. It was recognized as a radioactive element in 1898, thanks to the radioactivity research of English chemist Gerhard C. Schmidt and Marie Curie. There are 27 known isotopes of thorium, all of which are radioactive. The isotope with the longest half-life is 232Th, with a staggering half-life of 14 billion years. This explains the relative abundance of this primordial radioactive element on Earth. This particular isotope decays into 228Ra through alpha decay, while other elemental decay products of thorium isotopes include radon and actinium.
Thorium: Thorium is obtained from the minerals autunite, carnotite, monazite, samarskite, and uraninite or pitchblende (uranium dioxide).
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106. Protactinium - About Protactinium: Protactinium, a radioactive actinide, is a scarce and intriguing element. Despite its scarcity, with only trace amounts found in uranium ore, it has a significant place in the scientific world. Its decay chain leads to actinium, hence the name Proto-actinium. The most stable and abundant isotope, Protactinium-231, has a half-life of 32,760 years and is produced through the decay chain of Uranium-235.
Although Protactinium has no known commercial or industrial uses, it plays a role in scientific research. For instance, naturally occurring isotopes of Protactinium in water, along with uranium and thorium, are used to date sediments and model geological processes. However, it's considered an undesirable byproduct in thorium-based nuclear reactors due to its radioactivity and toxicity.
The discovery of Protactinium is credited to multiple scientists. Kasimir Fajans and Oswald Helmuth Gohring first identified it in 1913. However, it wasn't until 1917 when a stable isotope was discovered by Otto Hahn, Lise Meitner, Frederick Soddy, and John Cranston that full credit for the discovery was assigned. The first isolation of the element is attributed to Aristid V. Grosse in 1934. The element took its final form in the periodic table in 1949 when Protoactinium was shortened to Protactinium, filling the last remaining gap in early versions of Mendeleev's periodic table.
Protactinium is a bright, shiny metal that forms compounds with halogens and hydrogen. Despite its position between useful elements like thorium and uranium on the periodic table, Protactinium itself has limited utility due to its scarcity, radioactivity, and toxicity. It has twenty-nine known isotopes, all of which are radioactive and decay into actinium via alpha or beta chains, depending on the isotope number. Despite its rarity, it can be found in minute amounts throughout Earth's biosphere.
Protactinium: Protactinium is found in minute quantities in uranium minerals and ores, but it must be created artificially in any significant quantity.
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107. Uranium - About Uranium: Uranium, predominantly found in oxide minerals, was first isolated by Martin Heinrich Klaproth in 1789 from a mineral called pitchblende. He named the element after the planet Uranus. Before Klaproth's discovery, pitchblende was used to color glass and ceramics. Uranium glass, which appears yellow or green under white light and fluoresces bright green under ultraviolet light, is negligibly radioactive and considered harmless.
Uranium is the second heaviest naturally occurring element, with plutonium being the heaviest. All natural isotopes of uranium are unstable, but most decay slowly. Despite its association with dangerous radioactivity, uranium itself is only weakly radioactive. It is found in nature as uranium-238 (~99.3%) and uranium-235 (~0.7%), the latter of which can undergo nuclear fission and sustain a fission chain reaction in a nuclear reactor or nuclear weapon. Uranium is also notable for its high density, higher than lead and surpassed by only a few elements.
The phenomenon of radioactivity was discovered through the study of uranium salts by Henri Becquerel and his colleagues Marie and Pierre Curie in 1896. They were awarded the Nobel Prize for their discovery in 1903. Uranium only presents a significant hazard to life when it is ingested, inhaled, or absorbed through the skin. Uranium toxicity is caused by both low-level but persistent radiation and the chemical toxic effects of the metal.
Uranium's most familiar use is in nuclear energy and weapons, exploiting the fissile nature of uranium-235 to produce massive amounts of energy. Research on sustained nuclear fission began in 1934 under Enrico Fermi, and the first artificial self-sustained nuclear chain reaction was achieved in 1942 as part of the Manhattan project.
Uranium enrichment is required for fission reactions, as only the rarer uranium-235, not the more common uranium-238, can sustain fission. The enrichment process separates uranium isotopes in the form of uranium hexafluoride by weight using high-powered centrifuges, producing uranium compounds enriched in uranium-235. The degree of enrichment depends on the intended use: nuclear power plants typically use natural uranium or uranium with less than a 20% concentration of uranium-235, while weapons-grade uranium is highly enriched.
The product left over following uranium enrichment is termed depleted uranium, which is used widely in military applications as both armor and munitions due to its high density. In civilian applications, depleted uranium is used primarily for shielding from high-energy radiation sources.
Uranium is commercially obtained from the extraction and processing of uranium-bearing minerals such as uraninite. The ores are processed to produce a powdered form of uranium oxide known as "yellowcake". Where enriched uranium is required, yellowcake is treated with various chemicals to produce uranium hexafluoride, known as "hex" in the nuclear industry. Uranium hexafluoride is highly toxic and reactive, and is hazardous to store, but is the primary raw material for all uranium enrichment techniques.
Uranium: Uranium is obtained from the minerals autunite, carnotite, monazite, samarskite, and uraninite or pitchblende (uranium dioxide).
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108. Neptunium - About Neptunium: Neptunium, a highly reactive radioactive actinide, was theorized to exist long before it was synthesized. Dmitri Mendeleev first proposed its existence in the 1870s, but it wasn't until 1940 that Edwin McMillan and Philip H. Abelson created the first observable neptunium element via neutron bombardment of uranium at the Berkeley Radiation Laboratory. Neptunium is extremely scarce in nature and can only be found in trace amounts in uranium ores within the Earth's crust. As such, neptunium is primarily available through neutron bombardment of uranium and is also produced as a by-product in nuclear reactors. It was the first transuranium element to be synthesized.
The most stable isotope of neptunium, 237Np, has a half-life of over two million years and decays into thallium and bismuth, primarily through alpha decay. Though neptunium has limited practical uses, Oak Ridge National Laboratory sells certain quantities for legal uses. It is widely used as a precursor step in the generation of 238Pu, an element often used in radioisotope thermoelectric generators to power deep-space spacecraft such as Voyager and Cassini-Huygens. Neptunium, as a standalone element, is primarily used in detectors of high-energy (MeV) neutrons.
Recent research has shown that neptunium could be used as an atomic weapon with a critical mass around 60 kilograms. With about 60,000 kilograms of neptunium being produced as a byproduct each year, the Federal government recently made plans to store isolated neptunium in nuclear-waste disposal sites. After 10,000 years, due to its long half-life, neptunium will become the dominant element remaining in nuclear waste being produced and stored today.
Neptunium is known to oxidize quickly and produce compounds with several other elements, including unusual metal-metal compounds with aluminum and beryllium. It is primarily reactive with oxygen, steam or acid but does not react to alkalis. There are no known uses for any of these compounds outside of fundamental scientific research. Nineteen radioisotopes of neptunium have been observed. Excluding 237Np, the half-life of these isotopes ranges from 3 milliseconds (225Np) to 154,000 years (236Np).
Neptunium (Netunium): Neptunium is found in minute quantities in uranium minerals and ores, but it must be created artificially in any significant quantity.
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109. Plutonium - About Plutonium: Plutonium, a member of the actinide series, is highly radioactive and stands out from its peers by being one of only three primary fissile isotopes (239Pu) in use, the others being 233U and 235U. These isotopes can produce and sustain a nuclear chain reaction when struck by a slow-moving neutron. Remarkably, just one kilogram of 239Pu can produce an explosion equivalent to 21,000 tons of chemical explosives.
Plutonium's primary applications are in weapons and power or fuel generation, with its suitability for these uses determined by the fractional amount of spontaneously fissile 240Pu in the system. Weapons-grade plutonium has the smallest amount of 240Pu dilution (7%), while power-grade plutonium has the largest amount (>19%). Other isotopes, such as 238Pu and 233Pu, have been used for specific applications, including in radioisotope thermoelectric generators on deep-space spacecraft and power systems on lunar equipment during the Apollo program.
The most stable isotope of plutonium, 244Pu, has a half-life of around 80 million years, long enough for trace amounts to remain present in the Earth's crust. The scarcity of naturally occurring plutonium necessitated its discovery in the laboratory. First incorrectly identified by Enrico Fermi in 1934, plutonium was synthesized by Glenn Seaborg under Edwin McMillan's leadership at the Berkeley Radiation Laboratory in 1940 through deuteron bombardment of uranium.
The fact of plutonium's existence was not publicly known until 1946, after the conclusion of the Manhattan Project. The United States' first atomic weapon test, "Trinity", and the second atomic bomb dropped on Japan, "Fat Man" in Nagasaki, used plutonium as their fissile material. The Nuclear Test Ban Treaty was partly enacted due to concerns over worldwide plutonium contamination.
Plutonium is a silvery-gray metal that oxidizes readily when exposed to air. When exposed to moist air, the volume of the plutonium sample can increase by 70%, causing powder to flake off and spontaneously ignite. Plutonium exhibits some unusual traits for a metal, including increased density when it melts and increased resistivity when its temperature is lowered. Its complex phase diagram makes machining plutonium difficult, as its states can easily change through several allotropes depending on environmental conditions.
Due to its reactive nature, plutonium forms compounds and metal alloys with many other elements, though none of these have any known uses outside of fundamental scientific research. Plutonium has twenty known isotopes, many of which have applications as described earlier. Over time, plutonium isotopes equal to 244 typically decay into uranium and neptunium via alpha decay, while isotopes greater than 244 typically decay into americium through beta decay.
Plutonium: Trace elements of plutonium are found in naturally occurring uranium ores. It is also found in minute quantities in uranium minerals and ores.
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110. Americium - About Americium: Americium, a transuranic element with a silvery-white hue and a density akin to lead, was first discovered in 1944 at the Argonne National Laboratory by a group of scientists under the leadership of Glenn T. Seaborg. It was later synthesized at the University of California, Berkeley. The process of separating americium from curium was so challenging that the researchers humorously referred to the elusive element as "pandemonium". Americium is positioned below europium on the final row of the periodic table, and its name was chosen to reflect this association with another element named after a continent.
Americium holds the unique distinction of being the only synthetic element to have found widespread consumer use: it serves as the ionization source in both commercial and residential smoke detectors. In addition, americium is utilized as a neutron source in neutron probes and neutron radiography, and as a portable source of gamma rays and alpha particles in various medical, scientific, and industrial applications. Americium also serves as a starting material for the production of other synthetic elements. Although americium is produced quite regularly in nuclear reactors, the intricate separation procedures required to isolate it from other elements ensure that the supply of the pure element remains limited, making the material relatively expensive.
Americium: Americium probably does occur naturally on Earth, but only in incredibly tiny amounts in uranium minerals where nuclear reactions may occasionally produce an atom.
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111. Curium - About Curium: Curium, a transuranic radioactive chemical element, was first created in 1944 by a team of scientists including Glenn T. Seaborg, Ralph A. James, and Albert Ghiorso at the University of California, Berkeley. This work was part of the Manhattan Project, and the discovery was kept secret until the conclusion of World War II. The unveiling of this discovery was planned for an American Chemical Society meeting, but Seaborg inadvertently revealed the news a few days early on a children's radio show when a sharp young listener asked if he had recently discovered any new transuranic elements. The element was named in tribute to Marie Sklodowska-Curie and Pierre Curie, who were pioneers in the field of radioactivity.
Curium serves as a fuel in radioisotope thermoelectric generators (RTGs) and as an alpha particle source in alpha particle X-ray spectrometers (APXS). APXS devices are primarily used in space exploration missions and have been included in several Mars rovers. Additionally, curium is utilized in the production of higher transuranic and transactinide elements.
Curium does not naturally occur on Earth and is typically produced by bombarding uranium or plutonium with neutrons in nuclear reactors. The pure element is hard, brittle, malleable, and has a lustrous silvery-white appearance.
Curium: Curium can be made in very small amounts by the neutron bombardment of plutonium in a nuclear reactor.
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112. Berkelium - About Berkelium: Berkelium, a transuranic element in the actinide series, exhibits a silvery-white color. It is not naturally occurring and was synthesized instead of being discovered. The synthesis was first achieved by the trio of Seaborg, Ghiorso, and Thompson at the University of California, Berkeley. This team was also responsible for the production of americium and curium in 1944, and they synthesized both berkelium and californium in 1949 and 1950. The naming of americium was influenced by its lanthanide analog, europium, which is directly above it on the periodic table. Similarly, berkelium was named after the city where it was discovered, just as its lanthanide analog, terbium, was named after the town of Ytterby, Sweden, where rare earth minerals were first located.
Berkelium is produced by bombarding uranium or plutonium with neutrons in a nuclear reactor. It can be separated from other reaction products with relative ease compared to some other transuranic elements. Berkelium is not a suitable candidate for use as nuclear fuel due to its extremely low fission cross section for thermal neutrons. Its primary use is in the production of other transuranic elements, and all other uses are in the context of basic research.
Berkelium is highly dangerous due to its high radioactivity and tendency to accumulate in skeletal tissue. Its use is limited to scientific research and the production of heavier actinides.
Berkelium: Berkelium has never been found naturally and less than a gram is produced each year.
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113. Californium - About Californium: Californium, a radioactive element, was first synthesized in 1950 by Stanley G. Thompson, Kenneth Street Jr., Albert Ghioirso, and Glen Seaborg at the Lawrence Berkeley National Laboratory at the University of California, which inspired its name. Despite being the sixth transuranic element to be artificially produced in a lab, it does occur naturally in minuscule amounts through the decay cycles of other elements. In fact, it is the heaviest element to do so; all elements that follow it on the periodic table are only present as a result of artificial synthesis processes. Californium is a silvery-white actinide metal with moderate chemical reactivity. Its f electrons are further removed from the valence electrons than those of the lighter actinides, causing it to behave similarly to the lanthanide elements by exhibiting divalent, trivalent, and tetravalent oxidation states in solid-state compounds. It is radioactive and is particularly toxic to humans due to its natural accumulation in skeletal tissue.
Californium is one of the few transuranic elements with practical applications, thanks to its relative stability and strong emission of neutrons. Neutrons can penetrate deeply through most materials, making neutron radiography a widely used technique to detect defects in aircraft and weapons components. Neutrons sourced from californium can also be used to initiate a nuclear reactor, scan nuclear fuel rods, and in radiation therapy for treatment-resistant cervical and brain cancers. Californium is also used in the synthesis of other transuranium elements, including ununoctium, which in 2006 became the heaviest element ever synthesized.
Californium: Californium is obtained by particle bombardment of plutonium.
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114. Einsteinium - About Einsteinium: Einsteinium, a member of the transuranic actinides, was discovered by a team led by Albert Ghiorso. Its discovery was among the debris collected from the fallout of Ivy Mike, the first successful hydrogen bomb test, in 1952. The discovery was kept confidential until 1955 due to the Cold War. The element was named einsteinium in honor of Albert Einstein. Today, einsteinium-253, the most common isotope of the element, is synthesized in a few high-power nuclear reactors from the decay of californium-253. Other isotopes are produced in small quantities by bombarding heavy actinides with light ions. The most stable isotope, einsteinium-252, has been challenging to produce in significant quantities, which has hindered the study of einsteinium's physical properties. However, it is known to be a soft, silvery, paramagnetic metal. The high radioactivity of einsteinium-253 emits a visible glow.
Due to the instability of the most easily produced isotope of einsteinium, the element has not been developed for commercial uses. Therefore, einsteinium is used exclusively in research, primarily in the production of other transuranium elements. Notably, the element mendelevium was first synthesized using einsteinium.
Einsteinium: Einsteinium is a synthetic chemical element; it has been discovered as a component of the debris of the first hydrogen bomb explosion in 1952.
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115. Fermium - About Fermium: Fermium, a highly radioactive transuranic actinide, was first identified in 1952 by a team of researchers from Berkeley, led by Albert Ghiorso. The team discovered Fermium while examining coral contaminated by the classified Ivy Mike nuclear test. However, due to the tensions of the Cold War, their discovery remained confidential until 1955. The element was named Fermium to honor the late Enrico Fermi for his significant contributions to nuclear physics.
The properties of Fermium are not well-known due to the minuscule amounts that have been produced. Following their initial experiment, Ghiorso's team successfully produced both Fermium and Einsteinium by bombarding plutonium-239. Fermium has a very short half-life, and as of now, it has no uses outside of scientific research due to its instability.
Fermium: Fermium can be obtained, in microgram quantities, from the neutron bombardment of plutonium in a nuclear reactor.
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116. Mendelevium - About Mendelevium: Mendelevium, a radioactive transuranic actinide, holds the distinction of being the first element synthesized atom by atom and the ninth transuranic element to be synthesized. This monumental achievement was accomplished by a team at the University of California Berkeley in 1955, resulting in the creation of a mere seventeen atoms. The synthesis process involved bombarding Einsteinium-253, a synthetic element that requires substantial effort to prepare and isolate in significant quantities, with alpha particles in the Berkeley lab's cyclotron. After the synthesis, the seventeen atoms of the new element were purified using ion-exchange chromatography. The discovery of the element and its naming in honor of Dimitri Mendeleev, the father of the modern periodic table, were recognized by the IUPAC later in 1955.
As one of the superheavy elements, Mendelevium is highly unstable. The most stable isotope has a half-life of approximately 55 days, while the initially synthesized isotope, Mendelevium-256, has a half-life of just 87 minutes. While Mendelevium has no commercial applications, it continues to be a subject of interest for scientific researchers due to its unique properties.
Mendelevium: Mendelevium was first obtained by particle bombardment of einsteinium.
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117. Nobelium - About Nobelium: Nobelium, a synthetic element in the actinide series, has a history marked by controversy and conflicting claims. Its discovery has been attributed to three different groups, and it was only in the 1990s that the IUPAC officially recognized Russia as the discoverer. The element was named Nobelium when scientists at the Nobel Institute in Sweden announced its discovery in 1957. However, their claim was later debunked, leading to a retraction, but the name Nobelium was retained. In 1959, researchers at UC Berkeley also claimed to have detected Nobelium, but their findings were not corroborated. Eventually, the Russian Joint Institute for Nuclear Research was acknowledged for correctly identifying Nobelium.
Nobelium has only been produced in minute quantities, and its most stable isotope has a half-life of just 58 minutes. There is still much to learn about this element, and it has not found any commercial applications. Nonetheless, it has been utilized in the study of nuclear fission due to its unique properties.
Nobelium: Nobelium is obtained by bombarding californium or curium with carbon.
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118. Lawrencium - About Lawrencium: Lawrencium, the final member of the actinide series, was initially synthesized in 1961 at the Lawrence Berkeley National Laboratory. The synthesis was led by Albert Chiorso and his nuclear-physics team, who bombarded a californium target with boron-10 and boron-11 using a heavy ion linear accelerator. The element was named Lawrencium to honor Ernest O. Lawrence, the creator of the first operational cyclotron. However, the initial experiments conducted by the Berkeley team did not yield all the necessary data to confirm the existence of an element. This data was later obtained from subsequent Berkeley experiments and research conducted by the Russian Joint Institute for Nuclear Research. In 1992, the IUPAC officially recognized both teams as co-discoverers of Lawrencium.
Due to the limited number of atoms ever produced and the extremely short half-lives of its isotopes, Lawrencium has not been studied extensively. As a result, it has no known commercial applications, and little is known about its properties.
Lawrencium: Lawrencium is obtained by bombarding californium or curium with carbon.
