THE UNUSUAL BONDING OF ACTINIDE SYSTEMS

The actinide elements have unusual bonding capabilities because of the availability of 5f, 6d, 7p, and 7s orbitals. Spectroscopic data along with predictive models are sufficiently complete to assign promotion energies for the various electronic configurations and the bonding contributions of the various types of electrons. The availability of a number of electronic configurations of comparable stability makes it possible for actinide metals to form complex crystal structures in which atoms in different lattice positions have different electronic configurations and different sizes. Bonding models provide predictions of thermodynamic properties that can be used to calculate phase diagrams of many systems with reasonable accuracy. The major challenge is provided by mixtures of actinide metals with platinum-group metals.