ELEMENTLE

Element 105 · Transition Metal

Dubnium

Period 7 · Group 5

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.

Three reasons Dubnium stands out

  1. 1

    Named after city in Russia known for nuclear research.

  2. 2

    Its discovery was a source of intense controversy between American and Soviet scientists, each claiming credit during the Cold War.

  3. 3

    Its most stable known isotope has a half-life of only about 28 hours.

Cold War chemistry measured in seconds

Dubnium atoms live just long enough for automated equipment to compare their behavior with niobium and tantalum. Laboratories at Dubna and Berkeley contested the discovery, producing a naming dispute settled only years later. The final name honors Dubna, the Russian nuclear-research center.

Dubnium at a glance
Atomic number / protons105
SymbolDb
Family (Elementle)Transition Metal
Classification (PubChem)Transition metal
Period7
Group5
Atomic mass (u)268.126
Standard stateBulk state not experimentally established
Electron configuration[Rn]7s2 5f14 6d3
Reported oxidation states5, 4, 3
Electronegativity (Pauling)Not available
Atomic radius (pm)Not available
First ionization energy (eV)Not available
Electron affinity (eV)Not available
Density (g/cm³)Not available
Melting pointNot available
Boiling pointNot available
Discovery (PubChem)1967

Values are reference data, not a specification for every temperature, pressure, or allotrope. Unknown properties are left unavailable. Superheavy-element predictions remain uncertain.

Sources & further reading

PubChem: Dubnium · Dubnium on Wikipedia

The introduction and original editorial story are adapted from Wikipedia contributors via Periodic-Table-JSON. Element descriptions and their adaptations are available under CC BY-SA 3.0. Numerical attributes use the PubChem periodic-table dataset, retrieved September 22, 2026.