Seaborgium (106)

Seaborgium is a synthetic element with the symbol Sg and atomic number 106, whose most stable isotope ²⁷¹Sg has a half-life of 1.9 minutes. A more recently discovered isotope ²⁶⁹Sg has a potentially slightly longer half-life (ca. 2.1 min) based on the observation of a single decay. Chemistry experiments with seaborgium have firmly placed it in group 6 as a heavier homologue to tungsten. This element is (also) not present in the environment at all. It has no uses outside of the research laboratories.

Name: Seaborgium Symbol: Sg Atomic number: 106 Atomic weight: [ 271 ] Standard state: presumably a solid at 298 K CAS Registry ID: 54038-81-2

Group in periodic table: 6 Group name: (none) Period in periodic table: 7 Block in periodic table: d-block Color: unknown, but probably metallic and silvery white or grey in appearance Classification: Metallic

Historical information

Seaborgium was discovered by Albert Ghiorso and others at 1974 in The Lawrence Berkeley Laboratory in California and the Livermore National Laboratory, USA.. The name originated from American nuclear chemist, and 1951 Nobel Prize (in chemistry) winner, Glenn T. "Seaborg."

The Berkeley/Livermore collaboration suggested the name seaborgium (Sg) to honor the American chemist Glenn T. Seaborg credited as a member of the American group in recognition of his participation in the discovery of several other actinides. The name selected by the team became controversial. The IUPAC adopted unnilhexium (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 when einsteinium was proposed as a name during Albert Einstein's life and a survey indicated that chemists were not concerned with the fact that Seaborg was still alive (he did not pass from the earth until 1999). In 1997, as part of a compromise involving elements 104 to 108, the name seaborgium for element 106 was recognized internationally. The name rutherfordium was assigned to element 104 instead

Transuranium elements such as seaborgium can be created artificially in particle accelerators. Isotopes of seaborgium have short half-lives of less than a second. The first report of element 106 came in 1974 from the Soviet Joint Institute for Nuclear Research and these were followed later by others from Berkeley in California, USA. Experiments at the same American institution confirmed the discovery in 1993. The Russian experiments involved the bombardment of lead isotopes with high energy ⁵⁴Cr ions while the American results followed the collision of ¹⁸O ions with ²⁴⁹Cf ions.

Physical properties

• Melting point: no data K
• Boiling point: no data K
• Density of solid: 23200 (predicted) kg m^-3

Orbital properties

• Ground state electron configuration:  [Rn].5f¹⁴.6d⁴.7s² (estimate based upon that of W)
• Shell structure:  2.8.18.32.32.12.2
• Term symbol:   ⁵D₀ (estimated on electronic structure)

Isolation

Only very small amounts of element 106, seaborgium, have ever been made. The first samples were made through a nuclear reaction involving fusion of an isotope of californium, ²⁴⁹Cf, with one of oxygen, ¹⁸O.

¹⁸O + ²⁴⁹Cf → ²⁶³₁₀₆Sg + 4 ¹n

Isolation of an observable quantity of seaborgium has never been achieved.

More recently, other isotopes have been made at the Paul Scherrer Institute (PSI) in Switzerland using neon atoms to bombard californium isotopes.

²⁴⁸Cf + ²²Ne → ²⁶⁶Sg + 4¹n