Insights into the bonding and electronic nature of heavy element materials

A long standing issue in heavy element science is what role electrons, especially the f-electrons, play in chemical and physical behaviors. This interest prevails not only for changes found between the two f-electron series and for the different elements in one series, but also for comparing a particular element's behavior in its elemental and combined states. Different types of experimental approaches over the years have been employed to probe and evaluate the nature of bonding and electronic configurations in these materials. In some instances the conclusions arrived from experiment and theory have differed, but theory and experiment have recently become more encompassing, sophisticated and in better accord with one another. Interpretations about the electronic interactions and bonding at ambient or elevated temperatures in the f-elements have been employed for many years and have generated important and guidelines Structural behaviors under pressure and the associated correlations with bonding via experimental methods have become especially enlightening in this regard. These experimental findings also generated increased theoretical efforts to probe these changes and offer new insights. Selected aspects of results obtained to date for f-electron materials using different experimental approaches and conditions will be examined and discussed here with regard to electronic configurations and the potential changes that occur in bonding. A useful approach in this regard is to employ correlations to establish trends as a function of electronic nature and configurations. Findings using this approach will be discussed here and compared to computational results for several materials.