An Overview about the Chemical Element Seaborgium

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Symbol: Sg

Atomic Number: 106

Atomic Mass: 271amu (atomic mass units)

Melting Point: Unknown

Boiling point: Unknown

Number of Protons: 106

Number of Electrons: 106

Number of Neutrons: 165

Classification: Transition Metal (man-made)

Crystal Structure: Unknown

Density @ 293K: Unknown

Color: Unknown

In 1974 there were two reports of the making of a "super-heavy" element with the atomic number 106. Super heavy elements are man-made elements with atomic numbers greater than 104. The element was named after the Nobel Prize winning American scientist Glenn Seaborg (1912-1999) who was instrumental in finding many man made chemical elements.

The first reported making of this element was made in June 1974 by the Joint Institute for Nuclear Research in Dubna, Russia. They bombarded targets made of lead-207 and lead-208 atoms with ions of chromium-54. This, they believed, formed atoms of seaborgium-259 with a half-life of 0.48 seconds.

The second report came from America in September 1974. A team of scientists from the Lawrence Berkeley Laboratory and the Lawrence Livermore National Laboratory under the guidance of Albert Ghiorso claimed to have made seaborgium-263. They used a Super-Heavy Ion Linear Accelerator to bombard a target made of californium-249 atoms with oxygen-18 ions. For each atom of seaborgium-263 produced for free neutrons were released. This isotope has a half-life of one second.

In 1993 the American team's experiments were confirmed. The discovery of seaborgium is now credited to the Lawrence Berkeley and Lawrence Livermore Laboratories. Until the experiments were confirmed seaborgium was known as unnilhexium with the symbol Unh. This was in accordance with the holding name system of the International Union for Pure and Applied Chemistry (IUPAC).

Since these initial discoveries a number of other isotopes of seaborgium have been made. These isotopes have mass numbers ranging from 258 to 273. Most recently the Paul Scherer Institute in Switzerland used neon-22 ions to bombard a target of californium-248 atoms to produce seaborgium-266 with a half life of 21 seconds.

All of the isotopes of this element are unstable. The most stable isotope produced to date is seaborgium-271 which has a half life of 1.7 minutes. This isotope decays by either alpha decay to form rutherfordium-267 or by spontaneous fission. The shortest half-life measured belongs to seaborgium-258 at 2.9 milliseconds. Seaborgium-258 also decays by either alpha decay or spontaneous fission.

With so very few atoms being available from these experiments and them having such short half-lives little of the physical or chemical characteristics of seaborgium are known. It is in Group 5 and Period 7 of the periodic table. The element is probably metallic and most likely to be gray or white in color.

It is highly unlikely that any industrial applications for the element will ever be found. It is of value in the field of scientific research into the "super-heavy" elements.


The Los Alamos National Laboratory (Chemical Division)

Web Elements

National Nuclear Data Center

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