Hassium (Hs)
Element 108 · Transition metal · atomic mass [269] u · group 8, period 7
Electron shells: 2, 8, 18, 32, 32, 14, 2
Hassium is the heaviest element whose chemistry has been studied in any detail. It behaves like a heavier osmium, forming a volatile tetroxide.
Researchers characterised hassium chemistry using literally single atoms, one at a time.
- Atomic number
- 108
- Atomic mass
- [269] u
- Electron configuration
- [Rn] 7s² 5f¹⁴ 6d⁶
- Group · period · block
- 8 · 7 · d
- Oxidation states
- +2, +3, +4, +5, +6, +8
- Electronegativity
- Not measured
- Melting point
- —
- Boiling point
- —
- Density
- Not measured
- State at 20 °C
- Unknown
- Appearance
- Unknown; presumed metallic
- Discovered
- Peter Armbruster, Gottfried Münzenberg and colleagues, 1984
108 protons, and 108 electrons when neutral
Mass number of the longest-lived isotope — no standard atomic weight exists
Iron group
What Hassium is used for
- Scientific research only
Atomic structure of Hassium
A neutral hassium atom has 108 protons and 108 electrons. Its most common isotope carries about 161 neutrons, which is where the mass number 269 comes from. Change the neutron count and you have a different isotope of hassium; change the proton count and you have a different element entirely.
Those electrons fill shells from the inside out: 2, 8, 18, 32, 32, 14, 2. In orbital notation that is [Rn] 7s² 5f¹⁴ 6d⁶. As a d-block element its valence count is variable, which is why it can form compounds in several oxidation states.
3D electron orbitals
See where Hassium's electrons actually are — a cloud of 26,000 points sampled from the probability density |ψ|², not a cartoon of a lobe.
Where Hassium sits in the periodic table
The d-block. Multiple stable oxidation states give them coloured compounds, catalytic ability and the strength that makes them the working metals of industry.
- Directly above: Osmium — same group, so similar chemistry with a smaller atom.
- One proton lighter: Bohrium.
- One proton heavier: Meitnerium.
Discovery and naming
Hassium was discovered by Peter Armbruster, Gottfried Münzenberg and colleagues in 1984. Its name comes from Latin Hassia, the German state of Hesse, which is also why its symbol (Hs) does not match its English name.
Every isotope of hassium is radioactive, so it has no standard atomic weight. Periodic tables show the mass number of its longest-lived isotope in square brackets instead.
Keep exploring
Atomic weight from IUPAC/CIAAW; physical properties from PubChem (US National Library of Medicine). Values that have never been measured are shown as “not measured” rather than estimated.
Related Calculators
Frequently Asked Questions
What is the atomic mass of Hassium?
Hassium has no stable isotope, so it has no standard atomic weight. Periodic tables instead show 269 in square brackets — the mass number of its longest-lived isotope.
How many protons, neutrons and electrons does Hassium have?
Hassium has 108 protons, because the atomic number is the proton count and that is what makes an atom Hassium at all. A neutral Hassium atom has the same number of electrons, 108. The neutron count varies by isotope; the most common one has about 161, since 269 − 108 = 161.
What is the electron configuration of Hassium?
The electron configuration of Hassium is [Rn] 7s² 5f¹⁴ 6d⁶. Its electrons are arranged 2, 8, 18, 32, 32, 14, 2 across 7 shells.
Is Hassium a metal?
Yes. Hassium is classified as a transition metal, on the metallic side of the table.
What group and period is Hassium in?
Hassium is in group 8 (the iron group), period 7, in the d-block. The group is its column and the period is its row.
What is the charge of Hassium?
Hassium most commonly forms a 8+ ion. Like most transition metals it has several accessible oxidation states, so the charge depends on the compound. Across all its compounds it shows oxidation states of +2, +3, +4, +5, +6, +8.
What is Hassium used for?
Scientific research only. Hassium is the heaviest element whose chemistry has been studied in any detail.
Who discovered Hassium, and where does its name come from?
Hassium (Hs) was discovered by Peter Armbruster, Gottfried Münzenberg and colleagues in 1984. The name comes from Latin Hassia, the German state of Hesse.
Is Hassium radioactive?
Yes. Every isotope of Hassium is radioactive — it has no stable form at all, which is why the periodic table shows its mass in square brackets rather than as a standard atomic weight.