Scandium, yttrium and lanthanum, situated in group 3 of the periodic table, are all soft, silvery-white metals, with high melting and boiling points. The melting points fall as we go down the group; the boiling points rise. Actinium too is a silvery-white metal, but differs from the other members of the group in being radioactive. The lanthanide and actinide elements, which occupy separate divisions, possess similar properties to those of lanthanum and actinium, but are given their own divisions because of differences in their electronic configurations.
Going down the group sees an increase in the reactivity of the group 3 metals. Yttrium tarnishes slowly in air becauses it forms a protective oxide layer, but lanthanum reacts much more quickly.
All burn readily, and tend to form colourless, trivalent salts.
