The heaviest elements to have been chemically characterized are seaborgium1 (element 106), bohrium2 (element 107) and hassium3 (element 108). All three behave according to their respective positions in groups 6, 7 and 8 of the periodic table, which arranges elements according to their outermost electrons and hence their chemical properties. However, the chemical characterization results are not trivial: relativistic effects on the electronic structure of the heaviest elements can strongly influence chemical properties4,5,6. The next heavy element targeted for chemical characterization is element 112; its closed-shell electronic structure with a filled outer s orbital suggests that it may be particularly susceptible to strong deviations from the chemical property trends expected within group 12. Indeed, first experiments concluded that element 112 does not behave like its lighter homologue mercury7,8,9. However, the production and identification methods10,11 used cast doubt on the validity of this result. Here we report a more reliable chemical characterization of element 112, involving the production of two atoms of 283112 through the alpha decay of the short-lived 287114 (which itself forms in the nuclear fusion reaction12 of 48Ca with 242Pu) and the adsorption of the two atoms on a gold surface. By directly comparing the adsorption characteristics of 283112 to that of mercury and the noble gas radon, we find that element 112 is very volatile and, unlike radon, reveals a metallic interaction with the gold surface. These adsorption characteristics establish element 112 as a typical element of group 12, and its successful production unambiguously establishes the approach to the island of stability of superheavy elements through 48Ca-induced nuclear fusion reactions with actinides.
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We are indebted to the staff of the U-400 cyclotron for providing intense beams of 48Ca. This work was supported in part by the Russian Foundation for Basic Research and by the Swiss National Science Foundation.
Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests.
This file contains Supplementary Notes and Supplementary Figures 1-7 describing the Monte-Carlo approach for the determination of the adsorption enthalpy of single atom amounts together with the statistical procedure applied to evaluate the adsorption enthalpy of element 112 on gold. Further details regarding the background of the measurement and a random rate analysis are included. (PDF 530 kb)
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Eichler, R., Aksenov, N., Belozerov, A. et al. Chemical characterization of element 112. Nature 447, 72–75 (2007). https://doi.org/10.1038/nature05761
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