Periodic table / Transition metals

107Bohrium

Bohrium is a transition metal (predicted) in group 7, period 7. It has only ever been made a few atoms at a time, so nobody has seen it as a solid, liquid or gas.

Shells: 2, 8, 18, 32, 32, 13, 2. A simple picture: electrons do not move in circles.

Symbol: Bh
Atomic number: 107 protons in the nucleus
Standard atomic weight: None. Bohrium has no stable isotopes, so the mass of a sample depends on which isotopes it holds.
Electron configuration: [Rn] 5f¹⁴ 6d⁵ 7s²
Electrons in each shell: 2, 8, 18, 32, 32, 13, 2
Group, period, block: 7, 7, d
Family: Transition metals (predicted)
State at 25 °C: not known
Electronegativity: no value
First ionisation energy: 742.9 kJ/mol (7.7 eV) (estimated by NIST)

Where these numbers come from

Atomic weight: IUPAC CIAAW, abridged standard atomic weights 2024. Electron configuration and ionisation energy: NIST Atomic Spectra Database. Family, state and electronegativity: PubChem. See Sources. Melting points, boiling points and densities are left out for now: published values differ between sources, and we will add them once each has been checked.