Nuclear and Radiochemistry

Chemistry of actinide elements

Except for the final actinide (lawrencium), which is a d-block element, all of the actinides are f-block elements. Actinium has been classified as d-block instead of lawrencium on occasion, however those who examine the topic prefer the classification with lawrencium in the d-block.  Although several have anomalous configurations in the ground state including the filling of the 6d shell due to interelectronic repulsion, the series mainly corresponds to the filling of the 5f electron shell.