The Actinides

Abstract

The fifteen elements of the actinide series form a unique group in two respects. Firstly, they are, taken as a whole, chemically unlike any other transition-metal series. They resemble in some respects the lanthanides, in other ways the 4d and 5d metals, but in many properties they resemble neither. Secondly, most of them do not occur in nature and must be made by transmutation. The general chemistry of the naturally occurring members thorium and uranium has long been known, but detailed studies of these two elements and the whole investigation of the remainder of the series was delayed until the introduction of atomic bombs and nuclear power stations during and after the Second World War. These projects required the manufacture of kilogram quantities of plutonium and isotopically enriched uranium, which in turn necessitated a detailed chemical and physical investigation of the whole series of metals as far as their availability permitted.