Periodic table / Transition metals
109Meitnerium
Meitnerium is a transition metal (predicted) in group 9, 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.
- Symbol
- Mt
- Atomic number
- 109 protons in the nucleus
- Standard atomic weight
- None. Meitnerium has no stable isotopes, so the mass of a sample depends on which isotopes it holds.
- Electron configuration
- [Rn] 5f14 6d7 7s2 (predicted, not measured)
- Electrons in each shell
- 2, 8, 18, 32, 32, 15, 2
- Group, period, block
- 9, 7, d
- Family
- Transition metals (predicted)
- State at 25 °C
- not known
- Electronegativity
- no value
- First ionisation energy
- not known
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.