Seaborgium (Sg)

• Element Symbol: Sg
• Atomic Number: 106
• Atomic Mass: 266
• Group # in Periodic Table: 6
• Group Name: Transition metals
• Period in Periodic Table: 7
• Block of Periodic Table: d-block
• Discovered by: Albert Ghiorso, Torbjørn Sikkeland, Almon E. Larsh, Robert M. Latimer (1974)

Seaborgium is a synthetic, radioactive element. It is a member of group 6 of the periodic table and, along with fellow group members molybdenum, chromium, and tungsten, is considered a transition metal. Although these four elements all share similar properties, seaborgium differs from the other three due to its synthetic nature. Seaborgium can be synthesized in a laboratory but does not exist freely in nature. It is also considered a transuranic element because it has an atomic number greater than 92, which is the atomic number of uranium. In addition, seaborgium is one of the transactinide elements, which have atomic numbers ranging from 104 to 118 and are all named for influential chemists and physicists (save for those that do not yet have names).

The events surrounding the discovery of seaborgium remained a subject of debate for decades, with scientists in both California and the Soviet Union claiming credit for the discovery, echoing the earlier debate over the discovery of the synthetic element rutherfordium. In the summer of 1974, a team of scientists at the Joint Institute for Nuclear Research in Dubna, Soviet Union, claimed they had discovered a new element. The group, led by Georgy Flerov, had bombarded isotopes of lead with chromium-54 ions in a particle accelerator called a cyclotron. This process produced ions of what the Dubna team believed to be a new element (the isotope seaborgium-259). Later on, in the autumn of 1974, scientists working at the Lawrence Radiation Laboratory at the University of California, Berkeley, also claimed to have discovered this new element, although in their claims the team doubted the scientific validity of the Dubna group’s findings. Led by Albert Ghiorso, the Berkeley team had bombarded atoms of californium-249 with oxygen-18 ions using the Super Heavy Ion Linear Accelerator (Super HILAC). This process resulted in the production of a different seaborgium isotope, as well as four free neutrons.

Eventually, the International Union of Pure and Applied Chemistry (IUPAC) intervened and conducted a thorough assessment of the claims made by both teams in order to determine which one deserved credit. In 1993 the IUPAC concluded that the Berkeley team should be credited with the discovery of the element. The Berkeley team proposed the name "seaborgium" in honor of the American chemist Glenn Seaborg, who took part in the discovery of many elements, including thorium, curium, californium, berkelium, plutonium, mendelevium, nobelium, and americium. However, this name proposal caused yet another debate, as the IUPAC had recently ruled that elements could not be named for a living person, and Seaborg was still alive at the time. In 1997 the IUPAC relented, and element 106 was dubbed seaborgium.

Physical Properties

Only a few atoms of seaborgium have so far been isolated, making its physical properties difficult to confirm. Therefore, the hardness, specific heat, and thermal and electrical conductivity of seaborgium are unknown. However, seaborgium is believed to behave much like its group 6 companions, and therefore various properties can be surmised based on knowledge of these other elements, particularly tungsten and molybdenum. The color of seaborgium cannot be confirmed, but it is most likely a metallic silvery-gray in color. The standard state of seaborgium at 298 kelvins (K) is solid. Its melting point is estimated to be about 3000 degrees Celsius (°C), and its boiling point is estimated at 5000 °C.

Chemical Properties

Much like its physical properties, the chemical properties of seaborgium are difficult to confirm due to the lack of observable quantities of the element. However, seaborgium is expected to behave much like, and therefore to have chemical properties similar to, the other group 6 elements. The predicted oxidation states of seaborgium are +6 and +4. Seaborgium has eleven known isotopes, none of which are stable or naturally occurring. They range in mass number from 258 to 271. The heavier isotopes are considered to be more stable, and seaborgium-271, with the longest known half-life (about 2.4 minutes), is the most stable of all of them. Lighter isotopes, such as seaborgium-258, persist for a few milliseconds. The isotopes of seaborgium generally decay through spontaneous fission, a type of radioactive decay undergone by heavy elements that results in the release of a large amount of energy. Seaborgium isotopes are also alpha emitters, meaning that they produce alpha particles (two protons and two neutrons bonded together), as a result of which they primarily produce isotopes of the element rutherfordium.

Applications

Seaborgium is not found in nature because it is a synthetic element that can only be created in a laboratory. There are currently no practical uses for seaborgium outside of scientific research, due to the small amounts of the element that are produced as well as its extremely short half-life and radioactivity. Seaborgium is most often created using nuclear bombardment techniques, in which californium-249 is bombarded with oxygen ions.

Bibliography

Emsley, John. Nature’s Building Blocks: An A–Z Guide to the Elements. 2nd ed. New York: Oxford UP, 2011. Print.

"Facts about Seaborgium." LiveScience. Purch, 22 Oct. 2013. Web. 12 Sept. 2015.

Hall, Linley Erin. The Transactinides: Rutherfordium, Dubnium, Seaborgium, Bohrium, Hassium, Meitnerium, Darmstadtium, Roentgenium. New York: Rosen, 2010. Print.

Haynes, William M., ed. CRC Handbook of Chemistry and Physics. 95th ed. Boca Raton: CRC, 2014. Print.

"Technical Data for Seaborgium." The Photographic Periodic Table of the Elements. Element Collection, n.d. Web. 12 Sept. 2015.