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Pr - Praseodymium

Praseodymium

 Praseodymium 
Pr
Atomic Number: 59
Atomic Weight: 140.9077
Element Type: Rare Earth Metal
Crystal Structure: Hexagonal
Melting Point: 931.0°C = 1707.8°F = 1204.15 K
Boiling Point: 3520.0°C = 6368.0°F = 3793.15 K
Critical Temp: °C = °F = K
Atomic Radius: 2.67 Å (Å = Angstrom = 10-10 m)
Covalent Radius: 1.65 Å
Electronegativity: 1.13

History

(Gr. prasios, green, and didymos, twin) In 1841 Mosander extracted the rare earthdidymia from lanthana; in 1879, Lecoq de Boisbaudran isolated a new earth, samaria, fromdidymia obtained from the mineral samarskite. Six years later, in 1885, von Welsbachseparated didymia into two others, praseodymia and neodymia, which gave salts of differentcolors. As with other rare earths, compounds of these elements in solution havedistinctive sharp spectral absorption bands or lines, some of which are only a fewAngstroms wide.


Sources

The element occurs along with other rare-earth elements in a variety of minerals.Monazite and bastnasite are the two principal commercial sources of the rare-earth metals.It was prepared in relatively pure form in 1931.






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(1882-1970)





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