Dubnium (Db)

Dubnium (symbol Db) is the chemical element with atomic number 105: a transition metal, radioactive, made artificially, with an atomic mass of 268 u. Discovered in 1967 (Dubna and Berkeley laboratories).

Dubnium is named after Dubna, a town north of Moscow that is home to the Joint Institute for Nuclear Research (JINR), one of the world's great element-making centers. Like its neighbor rutherfordium, it was fought over by the Soviets and the Americans. Only a very small number of atoms have ever been produced, detected one at a time. Its most stable isotope, dubnium-268, has a surprisingly long half-life of about 16 hours.

Key facts

Atomic number: 105
Symbol: Db
French name: Dubnium
Atomic mass: 268 u
Molar mass: [268] g/mol
Family: Transition metals
Position: period 7, group 5, d-block
State at 0 °C: Unknown
First ionization energy: 665 kJ/mol
Electron configuration: [Rn] 5f¹⁴ 6d³ 7s²
Radioactive: yes
Discovery: 1967, Dubna and Berkeley laboratories

Origin of the name

From Dubna, a Russian town home to a major nuclear research center.

What does dubnium look like?

Never observed in visible amounts; predicted to be a dense, silvery metal.

Where is dubnium found?

Absent from nature.

How is dubnium produced?

It is made in accelerators, for example by bombarding americium with neon (Dubna) or californium with nitrogen (Berkeley). Its longest-lived isotopes appear as decay products of heavier elements such as moscovium.

Top producers

Russia (Dubna)
United States (Berkeley)

What is dubnium used for?

Basic research only
Comparing its chemistry with that of niobium and tantalum

In everyday life

None — it exists only for moments in the lab

Role in living things

No biological role.

Hazards of dubnium

Radioactive, but produced atom by atom: no practical danger.

Cosmic origin

Human-made: Does not exist (or barely) in nature: synthesized in a reactor or accelerator.

History of dubnium

Dubna claimed its discovery in 1968 and proposed “nielsbohrium”; Berkeley produced it in 1970 and proposed “hahnium,” after Otto Hahn. In 1994, IUPAC even suggested “joliotium,” in honor of Frédéric Joliot-Curie. The final compromise of 1997 named it dubnium, recognizing Dubna's contribution.

Did you know?

For nearly thirty years, it went by three different names depending on the country and the era.
The name “hahnium” eventually disappeared, but for a time it had been proposed for element 108.
The 16-hour half-life of dubnium-268 came as a surprise: it is far longer than its lighter neighbors.

Isotopes of dubnium

No stable isotopes; yet some dubnium isotopes live for hours (16 h for dubnium-268), a record among the superheavy elements.

dubnium-262: radioactive, half-life 34 s. Used in the first studies of dubnium's chemistry.
dubnium-268: radioactive, half-life 16 h. The longest-lived known, a decay product of moscovium.

Related elements

Same family (transition metals): Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Yttrium (Y), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Technetium (Tc), Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Silver (Ag), Cadmium (Cd), Hafnium (Hf), Tantalum (Ta), Tungsten (W), Rhenium (Re), Osmium (Os), Iridium (Ir), Platinum (Pt), Gold (Au), Mercury (Hg), Rutherfordium (Rf), Seaborgium (Sg), Bohrium (Bh), Hassium (Hs).

Same column (group 5): Vanadium (V), Niobium (Nb), Tantalum (Ta).