ununoctium, artificially produced radioactive chemical
element; symbol Uuo; at. no. 118. Scientists from the Joint Institute for Nuclear Research in Dubna, Russia, and Lawrence Livermore National Laboratory in California collaborated in the discovery of ununoctium in experiments conducted in 2002 and 2005. They bombarded atoms of
californium-249 with ions of
calcium-48. Among the products of the bombardments were three atoms of ununoctium-294 (one atom in 2002 and two in 2005), each of which decayed in 0.9 milliseconds into an atom of
ununhexium by emitting an
alpha particle. No name has yet been adopted for element 118, which is therefore called ununoctium, from the Latin roots
un for one and
oct for eight, under a convention for neutral temporary names proposed by the International Union of Pure and Applied Chemistry (IUPAC) in 1980.
In 1999 a research team at the Lawrence Berkeley National Laboratory in Calif. bombarded lead-208 atoms with high-energy krypton-86 ions to create what an analysis showed to be three atoms of element 118 with mass number 293 and a half-life of less than a millisecond. In 2001, however, the team retracted its claim to have produced ununoctium after other laboratories failed to reproduce their results and after a reanalysis of the original data did not show the production of element 118. A subsequent investigation suggested that the original finding was the result of fraud on the part of one of the team scientists.
See also synthetic elements; transactinide elements; transuranium elements.
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