Scandium

Scandium is a chemical element with symbol Sc and atomic number 21. A silvery-white metallic transition metal, it has historically been sometimes classified as a rare earth element, together with yttrium and the lanthanoids. In 1879, Lars Fredrik Nilson and his team, found a new element with spectral analysis, in the minerals euxenite and gadolinite .

Due to the low availability and the difficulties in the preparation of metallic scandium, which was first done in 1937, it took until the 1970s before applications for scandium were developed. The positive effects of scandium on aluminium alloys were discovered in the 1970s, and its use in such alloys remains the only major application of scandium.

Characteristics

Scandium is more common in the sun and certain stars than on Mars, but it is the 23rd most common element in the sun. Scandium is more closely related to that of yttrium than that of aluminium and explains why scandium has been classified as a lanthanide-like element. The oxide Sc2O3 is weakly acidic and the hydroxide Sc(OH)3 is amphoteric

There are a few compounds known in which the oxidation state is less than 3. The cluster [Sc6Cl12]3− has a similar structure to that of the Nb6Cl12 cluster in which chlorine atoms bridge the 12 edges of an octahedron of metal atoms. Other sub-halides are known. The nature of the hydride ScH2 is not yet fully understood. It appears not to be a saline hydride of Sc(II), but may be a compound of Sc(III) with two hydrides and an electron which is delocalized in a kind of metallic structure. ScH can be observed spectroscopically at high temperatures in the gas phase.

Scandium forms a series of organometallic compounds with cyclopentadienyl, based on the Sc(Cp)2 motif. The chlorine-bridged dimer, [Sc(Cp)2Cl]2 is the starting point for the preparation of many compounds by replacement of the chlorine.