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106 dubniumseaborgiumbohrium


Name, Symbol, Number seaborgium, Sg, 106
Chemical series transition metals
Group, Period, Block 6, 7, d
Appearance unknown, probably silvery
white or metallic gray
Standard atomic weight (263)  g·mol−1
Electron configuration perhaps [Rn] 7s2 5f14 6d4
(guess based on tungsten)
Electrons per shell 2, 8, 18, 32, 32, 12, 2
Physical properties
Phase presumably a solid
Density (near r.t.) 35 (est.)  g·cm−3
Atomic properties
Crystal structure cubic body centered
Oxidation states 6, 5, 4, 3, 2, 1, −1 (mildly acidic oxide)
Atomic radius (calc.) 132  pm
Covalent radius 63 (calc.) pm
CAS registry number 54038-81-2
Selected isotopes
iso NA half-life DM DE (MeV) DP
271Sg syn 2.4 min α

Seaborgium (pronounced /siːˈbɔrgiəm/), also called eka-tungsten, is a chemical element in the periodic table that has the symbol Sg and atomic number 106. Seaborgium is a synthetic element whose most stable isotope 271Sg has a half-life of 2.4 minutes. Its chemistry probably resembles that of tungsten.


Element 106 was discovered almost simultaneously by two different laboratories. In June 1974, an American research team led by Albert Ghiorso at the Lawrence Radiation Laboratory at the University of California, Berkeley reported creating an isotope with mass number 263 and a half-life of 1.0 s, and in September 1974, a Soviet team led by G. N. Flerov at the Joint Institute for Nuclear Research at Dubna reported producing an isotope with mass number 259 and a half-life of 0.48 s,

Because their work was independently confirmed first, the Americans suggested the name seaborgium to honor the American chemist Glenn T. Seaborg credited as a member of the American team along with Ghiorso, J. M. Nitschke, J. R. Alonso, C. T. Alonso, M. Nurmia, E. Kenneth Hulet, and R. W. Lougheed in recognition of his participation in the discovery of several other actinides. The name selected by the team became controversial. An international committee decided in 1992 that the Berkeley and Dubna laboratories should share credit for the discovery.

An element naming controversy erupted and as a result IUPAC adopted unnilhexium (pronounced /ˌjuːnɪlˈhɛksiəm/, symbol Unh) as a temporary, systematic element name. In 1994 a committee of IUPAC recommended that element 106 be named rutherfordium and adopted a rule that no element can be named after a living person. This ruling was fiercely objected to by the American Chemical Society. Critics pointed out that a precedent had been set in the naming of einsteinium during Albert Einstein's life. In 1997, as part of a compromise involving elements 104 to 108, the name seaborgium for element 106 was recognized internationally.


There are 12 known isotopes of Seaborgium, the longest-lived of which is 271Sg which decays through alpha decay and spontaneous fission. It has a half-life of 2.4 minutes. The shortest-lived isotope is 258Sg which also decays through alpha decay and spontaneous fission. It has a half-life of 2.9 ms.


External links

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