CHEMICAL-PROPERTIES OF ELEMENT-106 (SEABORGIUM)

The synthesis, via nuclear fusion reactions, of elements heavier than the actinides, allows one to probe the limits of the periodic table as a means of classifying the elements. In particular, deviations in the periodicity of chemical properties for the heaviest elements are pred icted as a consequence of increasingly strong relativistic effects on the electronic shell structure(1-7). The transactinide elements have n ow been extended up to element 112 (ref. 8), but the chemical properti es have been investigated only for the first two of the transactinide elements, 104 and 105 (refs 9-19). Those studies showed that relativis tic effect render these two elements chemically different from their l ighter homologues in the same columns of the periodic table (Fig. 1). Here we report the chemical separation of element 106 (seaborgium, Sg) and investigations of its chemical behaviour in the gas phase and in aqueous solution. The methods that we use are able to probe the reacti vity of individual atoms, and based on the detection of just seven ato ms of seaborgium we find that it exhibits properties characteristic of the group 6 homologues molybdenum and tungsten. Thus seaborgium appea rs to restore the trends of the periodic table disrupted by relativist ic effects in elements 104 and 105.