Basis of the solution chemistry of actinoids and lanthanoids

The studies on aqueous solutions of actinoids and lanthanoids, which are important basis of fuel reprocessing or waste processing and disposal, are reviewed. Characteristics of lanthanoid and actinoid elements including their electronic configuration and valence orbitals, promotion of energy level of f orbitals (4f to 5d and 5f to 6d), the spread of f orbitals and the itinerancy are examined. Similarity and difference between lanthanoids and actinoids are discussed on the basis the difference of f and d electron orbitals. The chemistry of hydrated ions of lanthanoids and actinoids are discussed together with the absorption spectra. (T.H.)