has·si·um  (hä'sē-əm)  n. Symbol Hs An artificially produced radioactive element with atomic number 108 whose most long-lived isotopes have mass numbers of 264 and 265 with half-lives of 0.08 milliseconds and 2 milliseconds, respectively. Also called unniloctium. See Table at element. [From Medieval Latin Hassia, Hesse (German state containing Darmstadt, where the element was first synthesized).] |
hassium
an artificially produced element belonging to the transuranium group, atomic number 108. It was synthesized and identified in 1984 by West German researchers at the Institute for Heavy Ion Research (Gesellschaft fur Schwerionenforschung [GSI]) in Darmstadt. On the basis of its position in the periodic table of the elements, it is expected to have chemical properties similar to those of osmium.
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