Approximate correlations between physicochemical properties of different members of lanthanide and actinide series

Consideration is given to the reasons of criss-cross change of oxidation potentials, energies of interconfigurational transitions, ionization energies and other characteristics in lanthanide and actinide series. Correlations, connecting values, taken by one or another characteristic for different members of lanthanide or actinide series, are presented. The obtained relations enable to calculate properties of f-elements and their compounds on the basis of experimental data, available only for a part of f-series members