105
Db
Dubnium
268
Dubnium (Db)
Transition MetalGroup 5Period 7d-block-blockRadioactive
Dubnium is a chemical element with symbol Db and atomic number 105. It is named after the town of Dubna in Russia (north of Moscow), where it was first produced. It is a synthetic element (an element that can be created in a laboratory but is not found in nature) and radioactive; the most stable known isotope, dubnium-268, has a half-life of approximately 28 hours.
Latin name: Dubnium
Atomic Number
105
Atomic Mass
268 g/mol
Phase (STP)
Solid (predicted)
Electron Config.
[Rn] 5f¹⁴ 6d³ 7s²
General
SymbolDb
Atomic Number105
Atomic Mass268 g/mol
CategoryTransition Metal
Group5
Period7
Blockd-block
Electron Configuration[Rn] 5f¹⁴ 6d³ 7s²
Valence Electrons5
Colourmetallic (predicted)
Physical Properties
Phase (STP)Solid (predicted)
Density29 (predicted)
Melting Point3000 (predicted)
Boiling PointUnknown
Atomic Properties
Atomic Radius249 pm
Electronegativity1.3 Pauling
Oxidation States+5
Ion ChargeDb5+
Nuclear & Hazards
RadioactiveYes
Half-life28 hours (Db-268)
Abundance
In Earth's Crust0%
Discovery & History
Discovery Year1970
Discovered ByJoint Institute for Nuclear Research and Lawrence Berkeley Laboratory
Country of DiscoveryUSSR/USA
Isotopes of Dubnium
| Isotope | Abundance | Half-life | Decay |
|---|---|---|---|
| Db-262 | — | 34 seconds | α, SF, EC |
| Db-268 | — | ~30 hours | SF |