Dubnium
[Rn] 5f¹⁴ 6d³ 7s² · 2 · 8 · 18 · 32 · 32 · 11 · 2
An element named after the town outside Moscow where the Joint Institute for Nuclear Research sits. Dubnium was one of the main trophies of the Transfermium Wars, the thirty-year priority dispute between the USSR and the United States.
3D model
Bohr model: nucleus and electron shells from the real configuration. Valence electrons are highlighted.
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Atomic properties
- Atomic number
- 105
- Atomic mass
- 268 а.е.м. ≈
- Electron configuration
- [Rn] 5f¹⁴ 6d³ 7s²
- Electrons per shell
- 2 · 8 · 18 · 32 · 32 · 11 · 2
- Block
- d-block
- Group
- Vanadium group
- Period
- 7
- Electronegativity (Pauling)
- no data
- Electronegativity (Allen)
- no data
- Atomic radius
- no data
- Covalent radius
- 149 pm
- Van der Waals radius
- no data
- Ionisation energy 1
- 665 kJ/mol ≈
- Electron affinity
- no data
- Common oxidation states
- +5
- Oxidation states
- +5
Physical properties
- State at 25 °C
- unknown
- Density
- 21.6 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
- body-centred cubic (bcc) ≈
- 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 |
|---|---|---|---|
| 268Db | — | 1.28 d | СД |
| 270Db | — | 1 h | α |
Dubnium-268, half-life about 30 hours, is the longest-lived known isotope.
Discovery
- Year of discovery
- 1968
- Discovered by
- Dubna and Berkeley
- Where
- USSR and USA
- Origin of the name
- after Dubna, home of the Joint Institute for Nuclear Research
History
Dubna claimed the synthesis in 1968 and Berkeley in 1970. The Americans proposed hahnium after Otto Hahn, the Soviet physicists nielsbohrium. IUPAC settled in 1997 on a compromise: element 105 became dubnium.
Where it occurs
Absent from nature.
How it is produced
By nuclear fusion: americium-243 bombarded with neon-22 ions, or berkelium with oxygen. 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 into superheavy element chemistry
Curiosities
- Dubnium is the only element named after a Russian town.
- Chemical experiments showed dubnium behaves like tantalum, with noticeable relativistic deviations.
- The 1997 IUPAC compromise finally closed a thirty-year priority dispute.
- Ten elements of the table were synthesised or co-discovered at Dubna.