Bohrium
[Rn] 5f¹⁴ 6d⁵ 7s² · 2 · 8 · 18 · 32 · 32 · 13 · 2
An element named after Niels Bohr, whose atomic model explained why the periodic table has the shape it does. Bohrium's chemistry was worked out on a total of six atoms.
3D model
Bohr model: nucleus and electron shells from the real configuration. Valence electrons are highlighted.
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Atomic properties
- Atomic number
- 107
- Atomic mass
- 270 а.е.м. ≈
- Electron configuration
- [Rn] 5f¹⁴ 6d⁵ 7s²
- Electrons per shell
- 2 · 8 · 18 · 32 · 32 · 13 · 2
- Block
- d-block
- Group
- Manganese group
- Period
- 7
- Electronegativity (Pauling)
- no data
- Electronegativity (Allen)
- no data
- Atomic radius
- no data
- Covalent radius
- 141 pm
- Van der Waals radius
- no data
- Ionisation energy 1
- 740 kJ/mol ≈
- Electron affinity
- no data
- Common oxidation states
- +7
- Oxidation states
- +7
Physical properties
- State at 25 °C
- unknown
- Density
- 26.5 g/cm³ ≈
- Melting point
- no data
- Boiling point
- no data
- Speed of sound
- no data
Thermal properties
- Heat of fusion
- no data
- Heat of vaporisation
- no data
- Specific heat capacity
- no data
- Thermal conductivity
- no data
Mechanical properties
- Young's modulus
- no data
- Shear modulus
- no data
- Bulk modulus
- no data
- Poisson ratio
- no data
- Mohs hardness
- no data
- Brinell hardness
- no data
Electrical and magnetic properties
- Electrical resistivity
- no data
- Magnetic ordering
- no data
- Curie point
- no data
- Néel point
- no data
- Superconducting point
- no data
Crystal structure
- Crystal structure
- hexagonal close-packed (hcp) ≈
- Lattice constants
- no data
Abundance
- In the crust
- 0 mg/kg
- In the ocean
- 0 mg/L
- In the universe
- 0 mg/kg
- In the human body
- 0 mg/kg
Isotopes
| Isotope | Abundance | Half-life | Decay mode |
|---|---|---|---|
| 270Bh | — | 1 min | α |
| 274Bh | — | 44 s | α |
Bohrium-270, half-life about a minute, is the longest-lived known isotope.
Discovery
- Year of discovery
- 1981
- Discovered by
- Peter Armbruster, Gottfried Münzenberg and colleagues
- Where
- Darmstadt, Germany
- Origin of the name
- after Niels Bohr
History
Armbruster, Münzenberg and colleagues synthesised element 107 at Darmstadt in 1981. Nielsbohrium was proposed, but IUPAC settled on the shorter bohrium to avoid confusion with boron.
Where it occurs
Absent from nature.
How it is produced
By nuclear fusion: bismuth-209 bombarded with chromium-54 ions. It is made one atom at a time.
Role in living things
No biological role.
Safety
Only single atoms are ever handled.
Uses
Fundamental research
Curiosities
- Bohrium's chemistry was studied in 2000 on six atoms — it forms a volatile oxychloride, as rhenium does.
- The name was shortened from nielsbohrium to bohrium to keep it distinct from element 5.
- The Darmstadt GSI accelerator discovered six elements in a row, from 107 to 112.
- Bohr's 1913 model explained periodicity through the filling of electron shells.