Bohrium (Bh)
Element 107 · Transition metal · atomic mass [270] u · group 7, period 7
Electron shells: 2, 8, 18, 32, 32, 13, 2
Bohrium was made at the GSI laboratory in Darmstadt by fusing bismuth and chromium nuclei. Just six atoms were produced in the original experiment.
Chemists have confirmed bohrium forms a volatile oxychloride, exactly like rhenium above it.
- Atomic number
- 107
- Atomic mass
- [270] u
- Electron configuration
- [Rn] 7s² 5f¹⁴ 6d⁵
- Group · period · block
- 7 · 7 · d
- Oxidation states
- +3, +4, +5, +7
- Electronegativity
- Not measured
- Melting point
- —
- Boiling point
- —
- Density
- Not measured
- State at 20 °C
- Unknown
- Appearance
- Unknown; presumed metallic
- Discovered
- Peter Armbruster, Gottfried Münzenberg and colleagues, 1976
107 protons, and 107 electrons when neutral
Mass number of the longest-lived isotope — no standard atomic weight exists
Manganese group
What Bohrium is used for
- Scientific research only
Atomic structure of Bohrium
A neutral bohrium atom has 107 protons and 107 electrons. Its most common isotope carries about 163 neutrons, which is where the mass number 270 comes from. Change the neutron count and you have a different isotope of bohrium; change the proton count and you have a different element entirely.
Those electrons fill shells from the inside out: 2, 8, 18, 32, 32, 13, 2. In orbital notation that is [Rn] 7s² 5f¹⁴ 6d⁵. As a d-block element its valence count is variable, which is why it can form compounds in several oxidation states.
3D electron orbitals
See where Bohrium's electrons actually are — a cloud of 26,000 points sampled from the probability density |ψ|², not a cartoon of a lobe.
Where Bohrium sits in the periodic table
The d-block. Multiple stable oxidation states give them coloured compounds, catalytic ability and the strength that makes them the working metals of industry.
- Directly above: Rhenium — same group, so similar chemistry with a smaller atom.
- One proton lighter: Seaborgium.
- One proton heavier: Hassium.
Discovery and naming
Bohrium was discovered by Peter Armbruster, Gottfried Münzenberg and colleagues in 1976. Its name comes from Niels Bohr, which is also why its symbol (Bh) does not match its English name.
Every isotope of bohrium is radioactive, so it has no standard atomic weight. Periodic tables show the mass number of its longest-lived isotope in square brackets instead.
Keep exploring
Atomic weight from IUPAC/CIAAW; physical properties from PubChem (US National Library of Medicine). Values that have never been measured are shown as “not measured” rather than estimated.
Related Calculators
Frequently Asked Questions
What is the atomic mass of Bohrium?
Bohrium has no stable isotope, so it has no standard atomic weight. Periodic tables instead show 270 in square brackets — the mass number of its longest-lived isotope.
How many protons, neutrons and electrons does Bohrium have?
Bohrium has 107 protons, because the atomic number is the proton count and that is what makes an atom Bohrium at all. A neutral Bohrium atom has the same number of electrons, 107. The neutron count varies by isotope; the most common one has about 163, since 270 − 107 = 163.
What is the electron configuration of Bohrium?
The electron configuration of Bohrium is [Rn] 7s² 5f¹⁴ 6d⁵. Its electrons are arranged 2, 8, 18, 32, 32, 13, 2 across 7 shells.
Is Bohrium a metal?
Yes. Bohrium is classified as a transition metal, on the metallic side of the table.
What group and period is Bohrium in?
Bohrium is in group 7 (the manganese group), period 7, in the d-block. The group is its column and the period is its row.
What is the charge of Bohrium?
Bohrium most commonly forms a 7+ ion. Like most transition metals it has several accessible oxidation states, so the charge depends on the compound. Across all its compounds it shows oxidation states of +3, +4, +5, +7.
What is Bohrium used for?
Scientific research only. Bohrium was made at the GSI laboratory in Darmstadt by fusing bismuth and chromium nuclei.
Who discovered Bohrium, and where does its name come from?
Bohrium (Bh) was discovered by Peter Armbruster, Gottfried Münzenberg and colleagues in 1976. The name comes from Niels Bohr.
Is Bohrium radioactive?
Yes. Every isotope of Bohrium is radioactive — it has no stable form at all, which is why the periodic table shows its mass in square brackets rather than as a standard atomic weight.