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Sc - Scandium

Scandium

 Scandium 
Sc
Atomic Number: 21
Atomic Weight: 44.9559
Element Type: Transition Metal
Crystal Structure: Hexagonal
Melting Point: 1541.0°C = 2805.8°F = 1814.15 K
Boiling Point: 2836.0°C = 5136.8°F = 3109.15 K
Critical Temp: °C = °F = K
Atomic Radius: 2.09 Å (Å = Angstrom = 10-10 m)
Covalent Radius: 1.44 Å
Electronegativity: 1.36

History

(L. Scandia, Scandinavia) On the basis of the Periodic System, Mendeleev predicted theexistence of ekaboron, which would have an atomic weight between 40 of calcium and 48 oftitanium.

The element was discovered by Nilson in 1878 in the minerals euxenite and gadolinite,which had not yet been found anywhere except in Scandinavia. By processing 10 kg ofeuxenite and other residues of rare-earth minerals, Nilson was able to prepare about 2g ofhighly pure scandium oxide. Later scientists pointed out that Nilson's scandium wasidentical with Mendeleev's ekaboron.


Sources

Scandium is apparently much more abundant (the 23rd most) in the sun and certain starsthan on earth (the 50th most abundant). It is widely distributed on earth, occurring invery minute quantities in over 800 mineral species. The blue color of beryl (aquamarinevariety) is said to be due to scandium. It occurs as a principal component in the raremineral thortveitite, found in Scandinavia and Malagasy. It is also found in the residuesremaining after the extraction of tungsten from Zinnwald wolframite, and in wiikite andbazzite.

Most scandium is presently being recovered from thortveitite or is extracted as aby-product from uranium mill tailings. Metallic scandium was first prepared in 1937 byFischer, Brunger, and Grienelaus who electrolyzed a eutectic melt of potassium, lithium,and scandium chlorides at 700 to 800oC.Tungsten wire and a pool of molten zinc served as the electrodes in a graphitecrucible. Pure scandium is now produced by reducing scandium fluoride with calcium metal.

The production of the first pound of 99% pure scandium metal was announced in 1960.



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