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synthetic element | [History]
Hassium was first synthesized and identified in 1964 by the same G.S.I. Darmstadt Group who first identified Bohrium and Meitnerium. Presumably this element has chemical properties similar to osmium. Isotope 265108 was produced using a beam of 58Fe projectiles, produced by the Universal Linear Accelerator (UNILAC) to bombard a 208Pb target. Discovery of Bohrium and Meitnerium was made using detection of isotopes with odd proton and neutron numbers.Elements having even atomic numbers have been thought to be less stable against spontaneous fusion than odd elements. The production of 265108 in the same reaction as was used at G.S.I. was confirmed at Dubna with detection of the seventh member of the decay chain 253Es. Isotopes of Hassium are believed to decay by spontaneous fission, explaining why 109 was produced before 108. Isotope 265108 and 266108 are thought to decay to 261106, which in turn decay to 257104 and 253102. The IUPAC adopted the name Hassium after the German state of Hesse in September 1997. In June 2001 it was announced that hassium is now the heaviest element to have its chemical properties analyzed. A research team at the UNILAC heavyion accelerator in Darmstadt, Germany built an instrument to detect and analyze hassium. Atoms of curium-248 were collided with atoms of magnesium-26, producing about 6 atoms of hassium with a half-life of 9 sec. This was sufficiently long to obtain data showing that hassium atoms react with oxygen to form hassium oxide molecules. These condensed at a temperature consistent with the behavior of Group 8 elements. This experiment appears to confirm hassium’s location under osmium in the periodic table. |
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