Seaborgium (Element)

seaborgium sēbôr´gēəm [key], artificially produced radioactive chemical element; symbol Sg; at. no. 106; mass number of most stable isotope 271; m.p., b.p., sp. gr., and valence unknown. Situated in Group 6 of the periodic table , it is expected to have properties similar to those of tungsten .

The discovery of element 106 took place almost simultaneously in two different laboratories. In June, 1974, a Soviet team led by G. N. Flerov at the Joint Institute for Nuclear Research at Dubna reported bombarding lead-207 and lead-208 atoms with chromium-54 ions to produce an isotope with mass number 259 and a half-life of 7 msec. In Sept., 1974, an American research team led by A. Ghiorso at the Lawrence Berkeley National Laboratory reported bombarding californium-249 atoms with oxygen-18 ions to create an isotope with mass number 263 and a half-life of 0.9 sec. Because their work was independently confirmed first, the Americans suggested the name seaborgium to honor the American chemist Glenn T. Seaborg . An international committee decided in 1992 that the Berkeley and Dubna laboratories should share credit for the discovery. The syntheses of at least 12 isotopes of seaborgium, with half-lives ranging from 2.9 msec (Sg-258) to 1.9 min (Sg-271), have been confirmed.

In 1994 a committee of the International Union of Pure and Applied Chemistry (IUPAC), convened to resolve naming disputes for the transactinide elements , recommended that element 106 be named rutherfordium . In 1997, however, the name seaborgium for element 106 was recognized internationally.

See also synthetic elements ; transuranium elements .

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