Hassium

Hassium is named after Hesse (Hassia in Latin), the German state where the GSI laboratory in Darmstadt is located. It was first synthesised in 1984 at GSI by bombarding lead with iron ions.

• Atomic Number108108 protons, 108 electrons
• Atomic Mass269.1336 uOver 108× heavier than hydrogen
• State at Room TempSolidpredicted solid
• DensityNot measuredPredicted from periodic trends
• Melting / BoilingNot yet measuredDecays in milliseconds to hours
• Discovered1984First produced 1976s

What is Hassium?

Hs-269 has a half-life of approx. 16 seconds. Hassium is predicted to behave chemically like osmium, in the same Group 8. Chemistry experiments on individual atoms have confirmed some of its properties.

With 108 protons, Hassium sits in Group 8 of the periodic table, Period 7, in the superheavy transactinide region. Its properties are predicted largely from theory and from single-atom chemistry experiments, not from bulk measurements.

Fact Hassium (Hs, element 108) has only ever been produced a few atoms at a time. Each atom decays within seconds. No one has ever seen, touched or measured a weighable amount of hassium. Everything we know about it comes from detecting individual radioactive decays and theoretical calculations.

Where you find Hassium

On Earth

Hassium does not exist naturally. It is made only artificially in nuclear physics laboratories by firing beams of one heavy nucleus at another and watching for the rare collisions that fuse them together. The main laboratories capable of producing superheavy elements are JINR in Dubna (Russia), GSI in Darmstadt (Germany), RIKEN in Japan and Lawrence Livermore National Laboratory in California.

How we use Hassium

Hassium has no practical uses. Only a handful of atoms have ever been produced, each existing for a fraction of a second to a few minutes. Research focuses on understanding nuclear structure, testing theoretical models of the atom, and searching for the predicted "island of stability", a region of superheavy nuclei that may be significantly longer-lived than those currently known.

How it was discovered

Hs-269 has a half-life of approx. 16 seconds. Hassium is predicted to behave chemically like osmium, in the same Group 8. Chemistry experiments on individual atoms have confirmed some of its properties.

Deeper dive: superheavy elements and the island of stability

Nuclear physicists predict that certain combinations of protons and neutrons, "magic numbers", create particularly stable nuclei. For superheavy elements, a theoretical "island of stability" is predicted around element 114 (flerovium) or beyond, where nuclei with the right magic number of neutrons might have half-lives of years or even longer rather than milliseconds. So far, the search continues. Elements 113-118 were all officially confirmed and named in 2016, completing Period 7 of the periodic table. Whether an eighth period of elements beyond oganesson (118) can ever be made and studied remains one of the great open questions in chemistry and nuclear physics.

Superheavy elements are made by accelerating beams of lighter nuclei (often calcium-48, because of its convenient doubly-magic structure) to high energies and firing them at heavy targets (lead, bismuth, uranium, curium, californium). Very rarely, two nuclei fuse instead of bouncing apart. The fusion product is detected by its characteristic radioactive decay chain, a signature sequence of alpha decays each producing a known element, counted backwards to identify the original product.

Moving to 109 protons on the periodic table brings us to the next superheavy element.