109[278]MtMeitnerium
Meitnerium (Mt) — element 109transition metal · group 9, period 7
Meitnerium is a chemical element with the symbol Mt and atomic number 109. It is a transition metal in group 9, period 7 of the periodic table (the d-block), with a standard atomic mass of [278] u. At room temperature (25 °C) meitnerium is predicted to be of unknown state.
💡 Known for: Named after Lise Meitner, co-discoverer of nuclear fission.
# Meitnerium properties
| Symbol | Mt |
|---|---|
| Atomic number | 109 |
| Atomic mass | [278] u |
| Category | transition metal |
| Group | 9 |
| Period | 7 |
| Block | d-block |
| Electron configuration | [Rn] 5f¹⁴ 6d⁷ 7s² |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d⁷ 7s² |
| Electrons per shell | 2, 8, 18, 32, 32, 15, 2 |
| Protons / electrons | 109 / 109 |
| State at 25 °C | unknown |
| Melting point | unknown |
| Boiling point | unknown |
| Density | 37.4 g/cm³ (predicted) |
| Electronegativity (Pauling) | — |
| First ionization energy | — |
| Atomic radius | — |
| Discovered | 1982 |
Values for superheavy elements are theoretical predictions; none have been measured in bulk.
# Electron configuration of meitnerium
The electron configuration of meitnerium is [Rn] 5f¹⁴ 6d⁷ 7s², written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d⁷ 7s². Its 109 electrons fill 7 shells as 2, 8, 18, 32, 32, 15, 2, so the outermost shell holds 2 electrons. Because only a few atoms have ever been made, this configuration is a theoretical prediction.
# Related elements
HsHassiumprevious elementDsDarmstadtiumnext elementCoCobaltgroup 9RhRhodiumgroup 9IrIridiumgroup 9ScScandiumtransition metalTiTitaniumtransition metalVVanadiumtransition metalCrChromiumtransition metalMnManganesetransition metalFeIrontransition metalNiNickeltransition metalCuCoppertransition metal
# Meitnerium FAQ
What is the atomic number of meitnerium?
The atomic number of meitnerium is 109: every meitnerium atom has 109 protons in its nucleus. Its symbol is Mt.
What is the atomic mass of meitnerium?
The standard atomic mass of meitnerium is [278] u (the mass number of its longest-lived isotope, since it has no stable isotopes).
What is the electron configuration of meitnerium?
Meitnerium's electron configuration is [Rn] 5f¹⁴ 6d⁷ 7s² (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d⁷ 7s²), with 2, 8, 18, 32, 32, 15, 2 electrons per shell.
Is meitnerium a metal?
Yes. Meitnerium is a transition metal, one of the metals.
What is the melting point of meitnerium?
The melting point of meitnerium is not known. These values are predictions.
What is meitnerium used for / known for?
Named after Lise Meitner, co-discoverer of nuclear fission.