The Clinical Use of Lanthanoids

The Clinical Use of Lanthanoids

The lanthanoid series consists of 14 elements (cerium to lutetium) and they are also called f-block metals, as the valence shell of lanthanoids contains 4f orbitals. Lanthanoids are named after the element lanthanum (La), which itself is a d-block metal. Nevertheless, because of its very similar chemical behaviour, lanthanum is often also classified as a lanthanoid. The term rare earth metals describes the lanthanoid series together with lanthanum (La), scandium (Sc) and yttrium (Y).

The lanthanoid series is often given the symbol Ln and referred to the elements La–Lu.

The trivalent cation is the most stable oxidation state, as the lanthanoids tend to lose three electrons (6s² and 5d¹) because of their electronic configuration. The resulting trivalent cations contain a xenon (Xe) core with regard to their electronic configuration with the addition of varying numbers of 4f electrons. The 4f electrons can be found closer to the nucleus, whilst the 5s² and 5p⁶, which are full sub-shells, shield them. Trivalent lanthanoids are often referred to as triple positive charged noble gases (Table 9.1).