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 from Scandinavia.
Scandium is present in most of the rare earth element and uranium deposits, but it is extracted from these ores in only a few mines worldwide. 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 its only major application.
The properties of Sc compounds are intermediate between the properties of Al and Y, and there is a diagonal relationship between the behavior of Mg and Sc, just as there is between Be and Al. There has been controversy as to whether yttrium is in the same group as lanthanum or as lutetium. In the chemical compounds of the elements shown as group 3, above, the predominant oxidation state is +3. The ions M3+ will all have the electronic configuration of a noble gas, so it is reasonable that they should be in the same group of the periodic table. Most modern text-books place Sc, Y, La and Ac in the same periodic group. Scandium metal is hard and has a silvery appearance. It develops a slightly yellowish or pinkish cast when exposed to air. It is not resistant to weathering and dissolves slowly in most dilute acids. It does not react with a 1:1 mixture of nitric acid (HNO3) and hydrofluoric acid, HF, presumably due to the formation of an impermeable passive layer on the surface of the metal.
