Hassium (Hs)

Hassium (symbol Hs) is the chemical element with atomic number 108: a transition metal, radioactive, made artificially, with an atomic mass of 269 u. Discovered in 1984 (Peter Armbruster and Gottfried Münzenberg (GSI)).

Hassium takes its name from the German state of Hesse (Hassia in Latin), home to the GSI in Darmstadt, which created it in 1984. Calculations predict it would be the densest substance ever known, about twice as dense as lead… but only a few atoms of it have ever existed. Its most stable known isotope has a half-life of a few seconds to a few tens of seconds.

Key facts

Atomic number: 108
Symbol: Hs
French name: Hassium
Atomic mass: 269 u
Molar mass: [269] g/mol
Family: Transition metals
Position: period 7, group 8, d-block
State at 0 °C: Unknown
First ionization energy: 730 kJ/mol
Electron configuration: [Rn] 5f¹⁴ 6d⁶ 7s²
Radioactive: yes
Discovery: 1984, Peter Armbruster and Gottfried Münzenberg (GSI)

Origin of the name

From Hassia, the Latin name for Hesse, a German state.

What does hassium look like?

Never observed in visible amounts. It is predicted to be a silvery metal with a density of about 40 g/cm³, well above osmium, the current record holder among measured materials.

Where is hassium found?

Absent from nature.

How is hassium produced?

GSI obtained it by bombarding a lead-208 target with iron-58 ions in its UNILAC linear accelerator. Other, more neutron-rich isotopes are made by bombarding curium-248 with magnesium-26.

Top producers

Germany (GSI Darmstadt)
Russia (Dubna)

What is hassium used for?

Basic research only
Studying deformed “magic” nuclei

In everyday life

None — it exists only for moments in the lab

Role in living things

No biological role.

Hazards of hassium

Radioactive, but produced atom by atom: no practical danger.

Cosmic origin

Human-made: Does not exist (or barely) in nature: synthesized in a reactor or accelerator.

History of hassium

In 1984, Peter Armbruster and Gottfried Münzenberg at GSI detected three atoms of hassium-265. In 1994, IUPAC had proposed naming it “hahnium,” but the name hassium, chosen by the discoverers, was adopted in 1997.

Did you know?

In 2001, an international experiment at GSI showed, with seven atoms, that it forms a volatile tetroxide just like osmium, the element above it.
The hassium-270 nucleus is called “doubly magic”: its numbers of protons (108) and neutrons (162) give it special stability.
It is one of the few elements named after an administrative region.

Isotopes of hassium

No stable isotopes; hassium-270 is a “doubly magic” nucleus, slightly more stable than its neighbors.

hassium-265: radioactive, half-life 1.96 ms. The element's first synthesized isotope, in 1984.
hassium-269: radioactive, half-life 16 s. Used in the first experiments on hassium chemistry.
hassium-270: radioactive, half-life 9 s. A nucleus with especially well-filled shells of protons and neutrons.

Related elements

Same family (transition metals): Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Yttrium (Y), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Technetium (Tc), Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Silver (Ag), Cadmium (Cd), Hafnium (Hf), Tantalum (Ta), Tungsten (W), Rhenium (Re), Osmium (Os), Iridium (Ir), Platinum (Pt), Gold (Au), Mercury (Hg), Rutherfordium (Rf), Dubnium (Db), Seaborgium (Sg), Bohrium (Bh).

Same column (group 8): Iron (Fe), Ruthenium (Ru), Osmium (Os).