Hassium is a synthetic element with the symbol Hs and atomic
number 108. It is the heaviest member of the group 8 (VIII)
elements. The element was first observed in 1984. Experiments have
confirmed that hassium is a typical member of group 8 showing a
stable +8 oxidation state, analogous to osmium. Several isotopes
are known, with 269Hs being the longest-lived with a
half-life of ~10 s. More than 100 atoms of hassium have been
synthesized to date in various cold and hot fusion reactions, both
as a parent nucleus and decay product.
Hassium was first synthesized in 1984 by a German research team
led by Peter Armbruster and Gottfried Münzenberg at the Institute
for Heavy Ion Research (Gesellschaft für Schwerionenforschung) in
Darmstadt. The team bombarded a lead target with 58Fe
nuclei to produce 3 atoms of 265Hs in the reaction:
The IUPAC/IUPAP Transfermium Working Group (TWG) recognised the
GSI collaboration as official discoverers in their 1992 report.
Element 108 has historically been known as eka-osmium. During
the period of controversy over the names of the elements IUPAC
adopted unniloctium (symbol Uno) as a temporary element name for
this element. The name hassium was proposed by the officially
recognised German discoverers in 1992, derived from the Latin name
for the German state of Hesse where the institute is located (L.
hassia German Hessen). In 1994 a committee of IUPAC recommended
that element 108 be named hahnium (Hn), in spite of the
long-standing convention to give the discoverer the right to
suggest a name. After protests from the German discoverers, the
name hassium (Hs) was adopted internationally in 1997.
Eka-osmium was a temporary name used to refer to the element
that goes under osmium in the periodic table. The name "eka" was
used in the same way as in Mendeleev's predicted elements. During
the first half of the 20th century, "eka-osmium" referred to
plutonium, because the actinide concept, which postulates the
actinides form an inner transition series similar to the
lanthanides, had not then been proposed. Once the actinide concept
became widely accepted, the name "eka-osmium" was used for element
108.