rare earth metals

The elements of group 3 (formerly called group IIIb in North America and IIIa in Europe) include the elements scandium, yttrium, lanthanum and actinium; the lanthanoids; and the actinides. Because scandium and yttrium, despite their d electrons, behave more like lanthanoids than the metals of the transition series, they are now usually considered rare earth metals, together with lanthanum and the lanthanides. Gadolinium, which, along with its lanthanon series sibling terbium, substitutes a 4f electron with a single 5d-electron, and exhibits strong ferromagnetic qualities.