| Physical properties | Most of the chemical and physical properties of unniloctium (hassium) are unknown.What is known is that its most stable isotope (hassium-108) has the atomic weight (mass) ofabout 277. Hs-277 has a half-life of about 12 minutes, after which it decays into the isotopeseaborgium-273 through either alpha decay or spontaneous fission. Hassium is the last elementlocated at the bottom of group 8, and like element 107, it is produced by a “cold fusion”process that in hassium’s case is accomplished by “slamming” iron (Fe-58) into particles of theisotope of lead (Pb-209), along with several neutrons, as follows:
82Pb-209 + 26Fe-58 + neutrons = 108Hs-256 +α decay products. |
| Isotopes | There are a total of eight isotopes for unniloctium (hassium) with atomic massesranging from 263 to 277 and half-lives ranging from 0.8 milliseconds (Uno-264) to12 minutes (Uno-277). |
| Origin of Name | Named for the word Hassias, which is the Latin name for the German
state of Hesse. |
| 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. |
| Uses | Considering that such a small amount of hassium is produced, it has no commercial usesbeyond basic research in nuclear laboratories. |
| Definition | A transactinide element that is formed artificially. Symbol: Hs; p.n. 108; most stable isotope 265Hs (half-life 2 × 10–3s). |
| Definition | hassium: Symbol Hs. A radioactivetransactinide element; a.n. 108. Itwas first made in 1984 by Peter Armbrusterand a team in Darmstadt,Germany. It can be produced by bombardinglead-208 nuclei with iron-58nuclei. Only a few atoms have everbeen produced. The name comesfrom the Latinized form of Hesse, theGerman state where it was first synthesized. |
| Hazard | Because only a few atom of hassium are produced at a time, radiation hazard is not aproblem. |