Unusual high temperature behavior of neptunium and plutonium systems

The initial effort on the Manhattan Project to predict the properties of transuranium elements assumed that the lanthanides would serve as models. However, many unexpected differences have been found. With the extensive work on the electronic configurations of the gaseous atoms, it is now possible to understand the reasons for the different behavior of the 5f elements compared to the 4f elements. A review of these differences will be presented along with examples of other unexpected behavior such as the very strong generalized Lewis acid-base interactions of the 5f elements with the platinum group metals that provide techniques for preparation of pure metal samples. The thermodynamic properties of the transuranium metals and some of their compounds will be reviewed