Yttrium is a transition metal in Group IIIB and the 5th period. It has oxidation numbers ranging from 0 to +3. Other elements of Group IIIB are scandium (Sc), lanthanum (La) and actinium (Ac).
In 1794 the Finnish chemist J. Gadolin examined a mineral discovered in a quarry near the small town of Ytterby in Sweden, and he found a new oxide that was later named yttria. This was in fact a mixture of metal oxides, from which C.G. Mosander separated yttrium oxide in 1843. The first sample of yttrium metal was isolated in 1828 by the great chemist Wöhler. (Ytterby has given its name to four elements: yttrium, ytterbium, erbium, and terbium).
In the solid state, the metal has a hexagonal closest packed structure.
Since these elements - Sc, Y, and La - are the first in the transition metal series, their chemistry is somewhat atypical. In large part this is owing to the fact that they form only +3 ions. The variable oxidation numbers characteristic of transition metals are absent, and their simple salts are often colorless since they have no d electrons remaining.
The elements of Group IIIB are not as rare as once thought. Their abundances in the earth's crust are Sc, 25; Y, 31; and La, 35 ppm; this makes them about as abundant as cobalt.
Y and La are almost always associated with the rare earth elements (the lanthanides). Yttrium is chiefly recovered from monazite, a metal phosphate where the metal can be Y, La, or a lanthanide.
All the metals of Group IIIB tarnish easily in air, and all burn readily to give, for example, Y2O3. They all react with halogens at room temperature, and all reduce water to give the metal hydroxide and H2 gas. All react with acids to give the appropriate metal salt.
Yttrium has become important in the electronics industry, as it is the basis of the phosphor used to produce the red color on television screens. Many thousands of pounds of these phosphors are used annually. The oxide is also found in orange ceramic tiles. Yttrium garnets, such as Y2Al2O12, a substance referred to as YAG, has been used as a gemstone and as a laser material. Finally, "misch metal", a mixture of various rare earth metals, is used in lighter flints.