Bohrium (Bh)

Bohrium (symbol Bh) is the chemical element with atomic number 107: a transition metal, radioactive, made artificially, with an atomic mass of 270 u. Discovered in 1981 (Peter Armbruster and Gottfried Münzenberg (GSI)).

Bohrium is named after Danish physicist Niels Bohr, a pioneer of atomic structure. It was created in 1981 at GSI in Darmstadt, Germany, using a so-called “cold fusion” method developed by Yuri Oganessian. Only a handful of atoms are known, and its chemical behavior resembles that of rhenium. Its most stable known isotope has a half-life on the order of a minute.

Key facts

Atomic number: 107
Symbol: Bh
French name: Bohrium
Atomic mass: 270 u
Molar mass: [270] g/mol
Family: Transition metals
Position: period 7, group 7, d-block
State at 0 °C: Unknown
First ionization energy: 740 kJ/mol
Electron configuration: [Rn] 5f¹⁴ 6d⁵ 7s²
Radioactive: yes
Discovery: 1981, Peter Armbruster and Gottfried Münzenberg (GSI)

Origin of the name

In honor of the physicist Niels Bohr.

What does bohrium look like?

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

Where is bohrium found?

Absent from nature.

How is bohrium produced?

GSI bombards a bismuth-209 target with chromium-54 ions. In this “cold fusion,” the lead or bismuth target produces a nucleus with little excess heat, which needs to shed only a single neutron to settle down — improving its odds of survival. Its longest-lived isotopes come from the decay of tennessine.

Top producers

Germany (GSI Darmstadt)
Russia (Dubna)

What is bohrium used for?

Basic research only

In everyday life

None — it exists only for moments in the lab

Role in living things

No biological role.

Hazards of bohrium

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 bohrium

Dubna claimed the element in 1976, but it was the team of Peter Armbruster and Gottfried Münzenberg at GSI that provided convincing proof in 1981. The Germans proposed “nielsbohrium”; IUPAC preferred a shorter name and adopted bohrium in 1997.

Did you know?

In 2000, an experiment at the Paul Scherrer Institute (Switzerland) studied bohrium's chemistry with just six atoms, forming a volatile oxychloride.
GSI alone made six elements, from bohrium (107) to copernicium (112).
Some chemists found the name “bohrium” too close to “boron.”

Isotopes of bohrium

No stable isotopes; only a few dozen atoms of bohrium have ever been produced.

bohrium-262: radioactive, half-life 100 ms. The element's first synthesized isotope, in 1981 in Darmstadt, Germany.
bohrium-267: radioactive, half-life 17 s. Made possible the first chemical study of bohrium, in 2000.
bohrium-270: radioactive, half-life 1 min. Among the longest-lived known.

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), Dubnium (Db), Seaborgium (Sg), Hassium (Hs).

Same column (group 7): Manganese (Mn), Technetium (Tc), Rhenium (Re).