Meitnerium (Mt)
Unknown / predicted · d-block · period 7 · group 9
Never enough atoms to see; chemistry never measured.
Meitnerium (symbol Mt) is chemical element number 109, a unknown / predicted in group 9, period 7 of the periodic table. Its standard atomic weight is (278) and its electron configuration is [Rn] 5f14 6d7 7s2. Its state at room temperature is unknown, and it is radioactive. Named after Lise Meitner, who explained nuclear fission and was denied the Nobel Prize.
Properties
| Atomic number | 109 |
|---|---|
| Atomic mass | (278) |
| Category | Unknown / predicted |
| Block | d-block |
| Group · Period | 9 · 7 |
| Electron configuration | [Rn] 5f14 6d7 7s2 |
| Electrons per shell | 2, 8, 18, 32, 32, 15, 2 |
| State at 25 °C | unknown |
| Melting point | — |
| Boiling point | — |
| Density | — |
| Electronegativity (Pauling) | — |
| Radioactive | Yes — no stable isotope |
| Origin | synthetic |
| Discovered | 1982 · GSI Darmstadt |
Key facts about Meitnerium
- Named after Lise Meitner, who explained nuclear fission and was denied the Nobel Prize.
- One of the few elements named solely after a woman.
- First made from a single atom in 1982.
- No chemical experiments have ever been possible.
What Meitnerium is used for
None — research only.
Where it sits in the periodic table
Meitnerium is in group 9, period 7, of the d-block. Its electron configuration [Rn] 5f14 6d7 7s2 means its outermost shell holds 2 electrons, which is what places it here and explains much of its chemistry. See Meitnerium on the interactive table →
Meitnerium — frequently asked questions
What is Meitnerium used for?
None — research only.
Is Meitnerium radioactive?
Yes. Meitnerium has no stable isotope, so every form of it is radioactive.
What is the electron configuration of Meitnerium?
Meitnerium has the electron configuration [Rn] 5f14 6d7 7s2, which is 2, 8, 18, 32, 32, 15, 2 electrons per shell.
What group and period is Meitnerium in?
Meitnerium is in group 9, period 7, in the d-block. Its outer shell holds 2 electrons.
Who discovered Meitnerium?
Meitnerium was discovered in 1982 by GSI Darmstadt.