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Arsenic
Arsenic
Arsenic
is a chemical element with symbol As and atomic number 33. Arsenic
Arsenic
occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic
Arsenic
is a metalloid. It has various allotropes, but only the gray form is important to industry. The primary use of metallic arsenic is in alloys of lead (for example, in car batteries and ammunition). Arsenic
Arsenic
is a common n-type dopant in semiconductor electronic devices, and the optoelectronic compound gallium arsenide is the second most commonly used semiconductor after doped silicon. Arsenic
Arsenic
and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides
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Allotropy
Allotropy
Allotropy
or allotropism (from Greek ἄλλος (allos), meaning 'other', and τρόπος (tropos), meaning 'manner, form') is the property of some chemical elements to exist in two or more different forms, in the same physical state, known as allotropes of these elements. Allotropes are different structural modifications of an element;[1] the atoms of the element are bonded together in a different manner. For example, the allotropes of carbon include diamond (the carbon atoms are bonded together in a tetrahedral lattice arrangement), graphite (the carbon atoms are bonded together in sheets of a hexagonal lattice), graphene (single sheets of graphite), and fullerenes (the carbon atoms are bonded together in spherical, tubular, or ellipsoidal formations). The term allotropy is used for elements only, not for compounds. The more general term, used for any crystalline material, is polymorphism
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Cadmium
Cadmium
Cadmium
is a chemical element with symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, namely zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of its compounds, and like mercury, it has a lower melting point than the transition metals in groups 3 through 11. Cadmium
Cadmium
and its congeners in group 12 are often not considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. The average concentration of cadmium in Earth's crust
Earth's crust
is between 0.1 and 0.5 parts per million (ppm). It was discovered in 1817 simultaneously by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate. Cadmium
Cadmium
occurs as a minor component in most zinc ores and is a byproduct of zinc production
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Yttrium
Yttrium
Yttrium
is a chemical element with symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element".[4] Yttrium
Yttrium
is almost always found in combination with lanthanide elements in rare-earth minerals, and is never found in nature as a free element. 89Y is the only stable isotope, and the only isotope found in the Earth's crust. In 1787, Carl Axel Arrhenius found a new mineral near Ytterby
Ytterby
in Sweden
Sweden
and named it ytterbite, after the village. Johan Gadolin discovered yttrium's oxide in Arrhenius' sample in 1789,[5] and Anders Gustaf Ekeberg named the new oxide yttria
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Calcium
Calcium
Calcium
is a chemical element with symbol Ca and atomic number 20. An alkaline earth metal, calcium is a reactive pale yellow metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust and the third most abundant metal, after iron and aluminium. The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossilised remnants of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. The name derives from Latin calx "lime", which was obtained from heating limestone. Its compounds were known to the ancients, though their chemistry was unknown until the seventeenth century. It was isolated by Humphry Davy
Humphry Davy
in 1808 via electrolysis of its oxide, who named the element
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Scandium
Scandium
Scandium
is a chemical element with symbol Sc and atomic number 21. A silvery-white metallic d-block element, it has historically been classified as a rare earth element,[5] together with yttrium and the lanthanides. It was discovered in 1879 by spectral analysis of the minerals euxenite and gadolinite from Scandinavia. Scandium
Scandium
is present in most of the deposits of rare-earth and uranium compounds, but it is extracted from these ores in only a few mines worldwide. Because of the low availability and the difficulties in the preparation of metallic scandium, which was first done in 1937, applications for scandium were not developed until the 1970s. The positive effects of scandium on aluminium alloys were discovered in the 1970s, and its use in such alloys remains its only major application
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Krypton
Krypton
Krypton
(from Ancient Greek: κρυπτός, translit. kryptos "the hidden one") is a chemical element with symbol Kr and atomic number 36. It is a member of group 18 (noble gases) elements. A colorless, odorless, tasteless noble gas, krypton occurs in trace amounts in the atmosphere and is often used with other rare gases in fluorescent lamps. With rare exceptions, krypton is chemically inert. Krypton, like the other noble gases, is used in lighting and photography. Krypton
Krypton
light has many spectral lines, and krypton plasma is useful in bright, high-powered gas lasers (krypton ion and excimer lasers), each of which resonates and amplifies a single spectral line. Krypton
Krypton
fluoride also makes a useful laser
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Rubidium
Rubidium
Rubidium
is a chemical element with symbol Rb and atomic number 37. Rubidium
Rubidium
is a soft, silvery-white metallic element of the alkali metal group, with a standard atomic weight of 85.4678. Elemental rubidium is highly reactive, with properties similar to those of other alkali metals, including rapid oxidation in air. On Earth, natural rubidium comprises two isotopes: 72% is the stable isotope, 85Rb; 28% is the slightly radioactive 87Rb, with a half-life of 49 billion years—more than three times longer than the estimated age of the universe. German chemists Robert Bunsen
Robert Bunsen
and Gustav Kirchhoff
Gustav Kirchhoff
discovered rubidium in 1861 by the newly developed technique, flame spectroscopy. Rubidium's compounds have various chemical and electronic applications
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Strontium
Strontium
Strontium
is the chemical element with symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white yellowish metallic element that is highly reactive chemically. The metal forms a dark oxide layer when it is exposed to air. Strontium
Strontium
has physical and chemical properties similar to those of its two vertical neighbors in the periodic table, calcium and barium. It occurs naturally mainly in the minerals celestine, strontianite and is mined mostly from the first two of these
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Zirconium
Zirconium
Zirconium
is a chemical element with symbol Zr and atomic number 40. The name zirconium is taken from the name of the mineral zircon, the most important source of zirconium. The word zircon comes from the Persian word zargun زرگون, meaning "gold-colored".[5] It is a lustrous, grey-white, strong transition metal that resembles hafnium and, to a lesser extent, titanium. Zirconium
Zirconium
is mainly used as a refractory and opacifier, although small amounts are used as an alloying agent for its strong resistance to corrosion. Zirconium
Zirconium
forms a variety of inorganic and organometallic compounds such as zirconium dioxide and zirconocene dichloride, respectively. Five isotopes occur naturally, three of which are stable
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Argon
Argon
Argon
is a chemical element with symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas.[6] Argon
Argon
is the third-most abundant gas in the Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abundant as water vapor (which averages about 4000 ppmv, but varies greatly), 23 times as abundant as carbon dioxide (400 ppmv), and more than 500 times as abundant as neon (18 ppmv)
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Niobium
Niobium, formerly known as columbium, is a chemical element with symbol Nb (formerly Cb) and atomic number 41. It is a soft, grey, crystalline, ductile transition metal, often found in the minerals pyrochlore and columbite, hence the former name "columbium". Its name comes from Greek mythology, specifically Niobe, who was the daughter of Tantalus, the namesake of tantalum. The name reflects the great similarity between the two elements in their physical and chemical properties, making them difficult to distinguish.[2] The English chemist Charles Hatchett
Charles Hatchett
reported a new element similar to tantalum in 1801 and named it columbium. In 1809, the English chemist William Hyde Wollaston
William Hyde Wollaston
wrongly concluded that tantalum and columbium were identical
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Technetium
Technetium
Technetium
is a chemical element with symbol Tc and atomic number 43. It is the lightest element whose isotopes are all radioactive; none are stable, excluding the fully ionized state of 97Tc.[4] Nearly all technetium is produced synthetically, and only about 18000 tons can be found at any given time in the Earth's crust. Naturally occurring technetium is a spontaneous fission product in uranium ore and thorium ore, the most common source, or the product of neutron capture in molybdenum ores. The chemical properties of this silvery gray, crystalline transition metal are intermediate between rhenium and manganese, which it lies between in group 7 of the periodic table. The most common naturally occuring isotope is 99Tc. Many of technetium's properties were predicted by Dmitri Mendeleev before the element was discovered. Mendeleev noted a gap in his periodic table and gave the undiscovered element the provisional name ekamanganese (Em)
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Ruthenium
Ruthenium
Ruthenium
is a chemical element with symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most other chemicals. The Russian-born scientist of Baltic-German ancestry and a member of the Russian Academy of Science Karl Ernst Claus discovered the element in 1844 at Kazan
Kazan
State University in Russia
Russia
and named it after the Latin name of his homeland, Rus. Ruthenium
Ruthenium
is usually found as a minor component of platinum ores; the annual production is about 20 tonnes.[5] Most ruthenium produced is used in wear-resistant electrical contacts and thick-film resistors. A minor application for ruthenium is in platinum alloys and as a chemistry catalyst
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Rhodium
Rhodium
Rhodium
is a chemical element with symbol Rh and atomic number 45. It is a rare, silvery-white, hard, corrosion-resistant and chemically inert transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring isotope, 103Rh. Naturally occurring rhodium is usually found as the free metal, alloyed with similar metals, and rarely as a chemical compound in minerals such as bowieite and rhodplumsite. It is one of the rarest and most valuable precious metals. Rhodium
Rhodium
is found in platinum or nickel ores together with the other members of the platinum group metals
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Palladium
Palladium
Palladium
is a chemical element with symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, platinum, rhodium, ruthenium, iridium and osmium form a group of elements referred to as the platinum group metals (PGMs). These have similar chemical properties, but palladium has the lowest melting point and is the least dense of them. More than half the supply of palladium and its congener platinum is used in catalytic converters, which convert as much as 90% of the harmful gases in automobile exhaust (hydrocarbons, carbon monoxide, and nitrogen dioxide) into less noxious substances (nitrogen, carbon dioxide and water vapor)
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