Lanthanides: Group Trends

Trends in the properties of lanthanide metals and some of their compounds are outlined. The correlation of properties as a function of atomic number and as a function of total orbital angular momentum is discussed. The trends in metallic properties such as metallic radii and chemical reactivity are discussed and explanations of the trends given. The lanthanide contraction and its consequences on the structures adopted by simple salts and coordination complexes are summarized and representative examples given. The variations of a number of important thermochemical properties such as enthalpies of vaporization of the metals, hydration enthalpies, and entropies of the Ln³⁺ ions and enthalpies of formation of halides and oxides are outlined and discussed. The relationship of the stability of complexes as a function of atomic number and angular momentum L are described with representative examples of halide, aminocarboxylate, and carboxylate complexes.

Keywords: lanthanide contraction; ionic radii; thermodynamic quantities; complexes; Z plots; inclined W plots