Atomic number 107 · Transition metal
Bohrium Bh
Bohrium is a superheavy element named after the Danish physicist Niels Bohr, who laid the foundations of atomic structure theory. It was first convincingly made in 1981 at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, and sits in group 7 below manganese, technetium and rhenium.
Key properties
| Atomic number | 107 |
|---|---|
| Atomic weight | [270] (No stable isotope; mass number of a representative isotope in brackets) |
| Category | Transition metal |
| Group | 7 |
| Period | 7 |
| Block | d |
| State (25 °C, 1 atm) | Solid |
| Melting point | — |
| Boiling point | — |
| Density | — |
| Electronegativity (Pauling) | — |
| Atomic radius (van der Waals) | — |
| First ionization energy | — |
| Electron affinity | — |
| Oxidation states | 7, 5, 4, 3 |
| Discovered | 1981 |
Electron configuration
- Condensed
- [Rn]7s2 5f14 6d5
- Full
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f14 6s2 6p6 6d5 7s2
- Electrons per shell
- 2 · 8 · 18 · 32 · 32 · 13 · 2
Orbital diagram
Position in the table
Discovery
A Dubna group reported element 107 in 1976, but the claim was not conclusive. In 1981 Peter Armbruster and Gottfried Münzenberg's team at GSI bombarded a bismuth-209 target with chromium-54 ions, produced bohrium-262 and identified it firmly through its decay chain. This 'cold fusion' approach, in which the merged nucleus is formed with relatively little excitation energy, went on to give GSI a string of discoveries up to element 112.
GSI proposed the name 'nielsbohrium' (Ns). Because combining a first name and surname broke with convention, IUPAC settled on 'bohrium' in 1997.
Origin of the name
The element honours Niels Bohr, whose model placed electrons in fixed energy levels around the nucleus. The symbol is Bh. The originally proposed 'nielsbohrium' was trimmed to the surname alone.
Main uses
- Basic research: It has no uses outside science.
- Chemistry: In 2000, gas-phase experiments at the Paul Scherrer Institute in Switzerland formed a bohrium oxychloride and found that bohrium behaves like rhenium, as expected of a group 7 element.
Isotopes
There are no stable isotopes. The longest-lived known isotope is bohrium-270, with a half-life of roughly two to three minutes, observed in the decay chains of heavier elements. Bohrium-262, the isotope of the 1981 discovery, lasts about a tenth of a second.
In everyday life
It does not exist in nature; only a few atoms at a time are made in accelerators and they decay almost immediately, so it has no connection with daily life or health.
Good to know
- The first proposed name, 'nielsbohrium', combined Bohr's first name and surname.
- Bohrium opened a run of GSI discoveries stretching to element 112.
- Bohrium-270, its longest-lived known isotope, has a half-life of about two to three minutes.
Same group (7)
Data sources · Properties: PubChem Periodic Table (US NIH/NLM public data) · Atomic weights: CIAAW 2024 abridged standard atomic weights · Names: Wikidata (CC0); Korean names follow the Korean Chemical Society. Retrieved 2026-09-23.