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59. PraseodymiumName: Praseodymium
Praseodymium is soft, silvery, malleable, and ductile. It was prepared in relatively pure form in 1931. It is somewhat more resistant to corrosion in air than europium, lanthanum, cerium, or neodymium, but it does develop a green oxide coating that "spalls" away when exposed to air. The metal should be stored under an inert atmosphere or under mineral oil or petroleum. The rare-earth oxides, including Pr2O3, are among the most refractory substances known. It is a component of misch metal, used for lighter flints, and of the glass in welders' goggles. The name Praseodymium comes from the Greek prasios, meaning "green", and didymos, or "twin". In 1841, Mosander extracted the rare earth didymium from lanthana. In 1874, Per Teodor Cleve concluded that didymium was in fact two elements, and in 1879, Lecoq de Boisbaudran isolated a new earth, Samarium, from didymium obtained from the mineral samarskite. In 1885, the Austrian chemist baron C. F. Auer von Welsbach separated didymium into two elements, Praseodymium and Neodymium, which gave salts of different colors. Like all rare earths, praseodymium is of low to moderate toxicity. Praseodymium has no known biological role. Quick links
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