Hassium

Lore & Background

Hassium is a synthetic, highly radioactive element with the symbol Hs and atomic number 108. Its most stable known isotopes have half-lives of approximately ten seconds, though one isotope possesses magic numbers of protons and neutrons for deformed nuclei, granting it enhanced stability against spontaneous fission. As a superheavy element, it has only been produced in minuscule quantities in laboratories through the fusion of heavy nuclei with lighter ones; natural occurrences have been hypothesized but never observed. On the periodic table, hassium is a transactinide element belonging to period 7 and group 8, making it the sixth member of the 6d series of transition metals. Chemical experiments have shown that hassium behaves as the heavier homologue to osmium, readily reacting with oxygen to form a volatile tetroxide. While its chemical properties are only partially characterized, they align well with those of other group 8 elements. The element was discovered using cold fusion, a technique where the fused nuclei are more similar in mass, reducing excitation energy and neutron ejection, thereby creating heavier, more stable nuclei. This method was first tested in 1974 at the Joint Institute for Nuclear Research in Dubna, Russia, and later used in attempts to synthesize element 108 in 1978, 1983, and 1984. The 1984 experiment at Dubna produced a claim of synthesis, followed by a separate claim later that year from the Gesellschaft für Schwerionenforschung in Darmstadt, Germany. A 1993 report by the Transfermium Working Group concluded the Darmstadt findings were conclusive, and major credit was assigned to the German team. The element was named hassium after the German state of Hesse, home to the facility, with the name accepted in 1997.

Reader's Guide

Hassium is a synthetic, highly radioactive element with no natural occurrences confirmed, though its existence in nature has been hypothesized. Its most stable known isotopes have half-lives of about ten seconds, but one isotope, 270Hs, possesses magic numbers of protons and neutrons for deformed nuclei, granting it enhanced stability against spontaneous fission. Chemically, hassium has been only partly characterized, but experiments confirm it behaves as the heavier homologue to osmium, reacting readily with oxygen to form a volatile tetroxide, aligning with the chemistry of other group 8 elements. The element was discovered through cold fusion, a technique that uses target nuclei with magic numbers—such as lead-208—to reduce excitation energy and neutron ejection, producing heavier, more stable nuclei. This method was first tested at the Joint Institute for Nuclear Research (JINR) in Dubna, which attempted synthesis of element 108 in 1978, 1983, and 1984; the 1984 experiment yielded a claim of production. Later that year, the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt also reported synthesis. The Transfermium Working Group, formed by IUPAC and IUPAP, concluded in 1993 that the GSI report was conclusive, assigning major credit to the German scientists. GSI proposed the name hassium after the German state of Hesse, home to the facility, and this name was accepted in 1997.

Did You Know?

• Hassium is named after the German state of Hesse, home to the GSI facility.
• Its most stable known isotopes have half-lives of about ten seconds.
• The isotope 270Hs has magic numbers of protons and neutrons for deformed nuclei, giving it greater stability against spontaneous fission.
• Chemistry experiments have confirmed that hassium reacts readily with oxygen to form a volatile tetroxide.