ABSTRACT
The regular trend in ionic radii resembles that shown by the lanthanide elements, and it is possible to talk of an actiniae contraction similar to the lanthanide contraction and arising from a similar increase in effective nuclear charge due to poor screening by the f electrons. The actinide contraction means that the actinide elements should show similar ion exchange behaviour to the lanthanides, and this has been made use of in a striking way in the identification of the newer heavy elements. The elements beyond curium have all very similar properties chemically, and the methods of synthesis mean that they are formed in only small amounts in the presence of excess target material. The identification of the heavier elements depends upon detecting their characteristic radiation (which can be predicted theoretically).
