Scandium is a chemical element, with the symbol Sc and atomic number 21.
It was discovered in 1879 by spectral analysis of the minerals euxenite and gadolinite from Scandinavia. It is a rare-earth metal of Group 3 of the periodic table.
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. The global trade of scandium oxide is about 10 tonnes per year.
The properties of scandium compounds are intermediate between those of aluminium and yttrium. A diagonal relationship exists between the behavior of magnesium and scandium, just as there is between beryllium and aluminium. In the chemical compounds of the elements in group 3, the predominant oxidation state is +3.
Chemical Characteristics of Scandium
- It is a silvery white, moderately soft metal. It is fairly stable in air but will slowly change its colour from silvery white to a yellowish appearance because of formation of Sc2O3 oxide on the surface.
- It is susceptible to weathering and dissolves slowly in most dilute acids. It does not react with a 1:1 mixture of nitric acid (HNO3) and 48% hydrofluoric acid (HF), possibly due to the formation of an impermeable passive layer.
- The metal slowly dissolves in diluted acids except hydrofluoric acid, in which a protective trifluoride layer prevents further reaction.
- It is paramagnetic from 0 K (−273 °C, or −460 °F) to its melting point (1,541 °C, or 2,806 °F). It becomes superconducting at −273.1 °C (−459.6 °F) at pressures exceeding 186 kilobars.