Hassium (Hs)

Hassium is the heaviest element whose chemistry has been studied in any depth. In 2001 a team made a handful of atoms, let them react with oxygen, and showed the product deposited on a cold surface just as osmium tetroxide does — hassium tetroxide exists, and hassium is a group 8 metal. If anything ever gets weighed at this end of the table it will probably be hassium: theory suggests it may be the densest element of all, around 41 g/cm³, roughly twice osmium, though no one has ever measured it and no one is likely to.

Properties

Atomic number

108

Symbol

Hs

Mass number of most stable isotope

[269]

Category

Transition metal

Group

8

Period

7

Block

d-block

Electron configuration

[Rn] 7s² 5f¹⁴ 6d⁶

Electrons per shell

2, 8, 18, 32, 32, 14, 2

Oxidation states

+8, +6, +5, +4, +3, +2

Discovered

1984 by Peter Armbruster, Gottfried Münzenberg and colleagues at GSI Darmstadt

Electron configuration

Full

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d⁶

Noble gas shorthand

[Rn] 7s² 5f¹⁴ 6d⁶

Shells

K: 2 · L: 8 · M: 18 · N: 32 · O: 32 · P: 14 · Q: 2

What it is used for

• Research only; no application outside the laboratory

Hazards

• Intensely radioactive; exists only as individual atoms in an accelerator

Melting point, boiling point, density and electronegativity are omitted. The often-quoted density of 41 g/cm³ is a calculation from the predicted crystal structure, not a measurement, which is exactly why it is not in the density field. The mass given is the mass number of hassium-269, the longest-lived confirmed at roughly 16 seconds; some longer-lived isotopes have been reported and not yet confirmed. Named after Hassia, the Latin name for the German state of Hesse.

Several physical properties are not listed for hassium because no bulk sample has ever existed. Only a handful of atoms have been produced, often with half-lives measured in seconds, so published melting points and densities for elements in this range are calculations rather than measurements. They are omitted rather than presented as observed values.

Neighbours in the table

Group 8

Elements in the same group share their outer electron count, which is why they behave similarly in reactions. Hassium sits in group 8 with iron, ruthenium, osmium.