Chemical investigation of hassium (element 108)

Abstract

The periodic table provides a classification of the chemical properties of the elements. But for the heaviest elements, the transactinides, this role of the periodic table reaches its limits because increasingly strong relativistic effects on the valence electron shells can induce deviations from known trends in chemical properties^1,2,3,4. In the case of the first two transactinides, elements 104 and 105, relativistic effects do indeed influence their chemical properties⁵, whereas elements 106 and 107 both behave as expected from their position within the periodic table^6,7. Here we report the chemical separation and characterization of only seven detected atoms of element 108 (hassium, Hs), which were generated as isotopes ²⁶⁹Hs (refs 8, 9) and ²⁷⁰Hs (ref. 10) in the fusion reaction between ²⁶Mg and ²⁴⁸Cm. The hassium atoms are immediately oxidized to a highly volatile oxide, presumably HsO₄, for which we determine an enthalpy of adsorption on our detector surface that is comparable to the adsorption enthalpy determined under identical conditions for the osmium oxide OsO₄. These results provide evidence that the chemical properties of hassium and its lighter homologue osmium are similar, thus confirming that hassium exhibits properties as expected from its position in group 8 of the periodic table.