Hassium holds its place at the table.
Hassium, with 108 protons in each atom, is the heaviest element yet to have its chemical properties analyzed. First created in 1984, hassium doesn't exist in nature--it must be made by combining the nuclei of lighter elements.
Suspecting that hassium has properties similar to osmium and other so-called group 8 elements, chemists placed hassium on the periodic table directly below osmium. Such placement, however, relied only on theoretical predictions, says Heino Nitsche of the Lawrence Berkeley (Calif.) National Laboratory. No one had actually observed hassium behavior--until now.
Nitsche and his colleagues in Berkeley worked with researchers at the Paul Scherrer Institute in Villigen and the University of Bern in Switzerland and the Institute of Nuclear Chemistry in Mainz, Germany.
The team recently built and installed an instrument at the UNILAC heavy-ion accelerator in Darmstadt, Germany, that can detect and analyze hassium. When the researchers slammed atoms of the artificial isotope curium-248 with magnesium-26 atoms, they ended up with at least six molecules of hassium.
Hassium has a half-life of just 9 seconds, but that's long enough to obtain crucial data, says Nitsche. For example, hassium atoms reacted with oxygen to form hassium oxide molecules that condensed at a temperature consistent with the behavior of group 8 elements, says Nitsche. The team measured other properties of hassium, such as the energy released as it decays.
The work would have pleased the early chemists who contributed to the periodic table, notes Nitsche, because it "shows that the structure of the periodic table holds even to these elements that they couldn't imagine at the time."
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|Title Annotation:||periodic table of chemical elements|
|Article Type:||Brief Article|
|Date:||Jun 23, 2001|
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