CHEMISTRY OF THE HEAVIEST ELEMENTS

Studies of the chemical properties of the elements at the uppermost en d of the periodic table are discussed. Some historical perspective is given, but major emphasis is on recent studies. Isotopes of these elem ents are short-lived and, therefore, must be studied near the site of production. They must be produced with charged-particle beams at accel erators rather than via neutron capture. The use of radioactive heavy actinide targets is often required and the number of atoms produced is so small that any chemistry to be performed must be done on an ''atom -at-a-time'' basis. Furthermore, a knowledge of their nuclear properti es is required in order to identify and detect them. To date, both gas and aqueous phase properties of elements as heavy as element 104 (rut herfordium) and element 105 (hahnium) have been investigated, even tho ugh their longest-lived known isotopes have half-lives of only 65 and 35 seconds, respectively. The experimental results show that their che mical properties cannot be simply extrapolated from the known properti es of their lighter homologs in the periodic table, emphasizing the im portance of obtaining additional experimental information for the heav iest elements to compare with predictions and help assess the influenc e of relativistic effects. The feasibility of the extension of chemica l studies to still heavier elements is also discussed.