Hassium
Transition metal · Period 7 · Group 8 · d-block
The superheavy element that behaves like osmium
- Atomic mass
- 269 u
- State at 25 °C
- Solid
- Electronegativity
- —
- Melting point
- —
- Boiling point
- —
- Configuration
- *[Rn] 5f14 6d6 7s2
Nucleus drawn at reduced count for clarity. Drag to rotate.
Hassium, explained
Video lesson in production
Bhavya’s explainer for this element will play here.
Overview
Hassium is a group 8 element under iron, ruthenium and osmium, with a predicted 7s2 6d6 configuration. Its signature chemistry is the +8 oxidation state. Osmium forms the volatile tetroxide OsO4, and in 2001 a team at GSI showed that hassium does the same, forming HsO4. The hassium tetroxide adsorbed at a slightly higher temperature than OsO4, meaning it is a little less volatile, in line with relativistic predictions.
Hassium is also important to nuclear physicists. Hassium-270, with 108 protons and 162 neutrons, is predicted to be a deformed doubly magic nucleus, with both proton and neutron numbers corresponding to closed shells in a non-spherical nucleus. Such shell effects stabilize nuclei that would otherwise fission instantly, and they are why superheavy elements exist at all. Hassium is predicted to be one of the densest elements, denser than osmium, though no visible sample will ever test that.
Discovery
Peter Armbruster and Gottfried Münzenberg's team at GSI made hassium in 1984 by bombarding lead-208 with iron-58 and detected three atoms of hassium-265. A Dubna group reported related results the same year, but IUPAC credited GSI. The name, proposed in 1992 and adopted in 1997, comes from Hassia, the Latin name of the German state of Hesse, where GSI is located.
- Where it’s found
- Hassium does not occur in nature; it is made in accelerators by fusing iron with lead or magnesium with curium.
- What it’s used for
- Group 8 chemistry studies
- Doubly magic nucleus research
- Relativistic effects research
- Superheavy volatility studies
- In living things
- Hassium has no biological role; it is radioactive and exists only as individual atoms.
- Safety
- Radioactive and made only a few atoms at a time; it decays within seconds.
How it compares
Where Hassium sits among all 118 elements on the trends that shape the table.
- ElectronegativityNo data
Not measured for this element
- Ionization energyNo data
Not measured for this element
- Atomic radiusNo data
Not measured for this element
- Electron affinityNo data
Not measured for this element
- Density40.7g/cm³
#1 of 114 elements with data · predicted
- Melting pointNo data
Not measured for this element
- Density
- 40.7 g/cm³
- Atomic radius
- —
- Covalent radius
- —
- Molar heat
- —
- Appearance
- —
- Discovered by
- Gesellschaft für Schwerionenforschung
Inside the atom
108 electrons arranged in 7 shells: 2 · 8 · 18 · 32 · 32 · 14 · 2.
Orbital diagram
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d6 · shorthand *[Rn] 5f14 6d6 7s2
- 1s2
- 2s2
- 2p6
- 3s2
- 3p6
- 4s2
- 3d10
- 4p6
- 5s2
- 4d10
- 5p6
- 6s2
- 4f14
- 5d10
- 6p6
- 7s2
- 5f14
- 6d6
Each box is an orbital holding up to two electrons of opposite spin. Highlighted subshells hold the valence electrons that decide how Hassium bonds.
Signature reactions
How the first atoms were made, and how they fall apart.
Nuclear · Cold fusion
GSI cold-fusion synthesis
Iron-58 fuses with lead-208 and the compound nucleus emits one neutron. GSI identified three hassium-265 atoms from their alpha-decay chains.
Conditions: iron-58 beam on lead-208, GSI UNILAC, 1984
Redox · Gas-phase oxidation
Formation of hassium tetroxide
Hassium-269 atoms made from curium-248 and magnesium-26 were oxidized in an oxygen-containing gas to HsO4. The molecules deposited on a cold detector array at a temperature showing HsO4 is slightly less volatile than OsO4.
Conditions: single atoms in He/O2 gas, GSI, 2001
Acid-base · Gas-solid
Sodium hassate formation
Like OsO4, hassium tetroxide reacts with hydroxide to form an oxo-anion complex, sodium hassate. This measured reaction confirms hassium behaves as a typical group 8 element.
Conditions: HsO4 passed over moist sodium hydroxide, 2003
Where you’ll meet it
Hesse
The German state of Hesse, Hassia in Latin, gives element 108 its name.
Photo: Wikimedia Commons
Osmium tetroxide
Hassium forms HsO4, the heavy analog of this volatile osmium compound.
Photo: Wikimedia Commons
Osmium
Osmium, directly above hassium in group 8, is its closest chemical reference.
Photo: Wikimedia Commons
GSI Helmholtz Centre for Heavy Ion Research
GSI made hassium in 1984 and studied its chemistry in 2001.
Photo: Wikimedia Commons
Research
No research on Hassium yet
When Bhavya publishes a project that studies Hassium, it will be linked here.