Introduction group IIIB

Group IIIB includes following elements: Scandium - [Sc], Yttrium - [Y], Lanthanum - [La], Actinium - [Ac].

In 1794 the Finnish chemist J. Gadolin, while examining a mineral that had recently been discovered in a quarry at Ytterby, near Stockholm, isolated what he thought was a new oxide (or “earth”) which A. G. Ekeberg in 1797 named yttria. In fact it was a mixture of a number of metal oxides from which yttrium oxide was separated by C. G. Mosander in 1843. The first sample of yttrium metal, albeit very impure, was obtained by F. Wohler in 1828 by the reduction of the trichloride by potassium.

Four years before isolating yttria, Mosander extracted lanthanum oxide as an impurity from cerium nitrate (hence the name from Greek - to hide), but it was not until 1923 that metallic lanthanum in a relatively pure form was obtained, by electrolysis of fused halides.

Scandium, the first member of the group, is also present in the Swedish ores from which yttrium and lanthanum had been extracted, but in only very small amounts and, probably for this reason, its discovery was delayed until 1879 when L. F. Nilsen isolated a new oxide and named it scandia. A few years later and with larger amounts at his disposal, P. T. Cleve prepared a large number of salts from this oxide and was able to show that it was the oxide of a new element whose properties tallied very closely indeed with those predicted by D. I. Mendeleev for ekaboron, an element missing from his classification. It was only in 1937 that the metal itself was prepared by the electrolysis of molten chlorides of potassium, lithium and scandium, and only in 1960 that the first pound of 99% pure metal was produced.

The final member of the group, actinium, was identified in uranium minerals by A. Debierne in 1899, the year after P. and M. Curie had discovered polonium and radium in the same minerals. However, the naturally occurring isotope, 227Ac, is a β-emitter with a half-life of 21.77 y and the intense γ-activity of its decay products makes it difficult to study.