Periodic TableMeitnerium (Mt)
Meitnerium is a transition metal with atomic number 109, in period 7 and group 9 of the periodic table. Its atomic mass is 278 u and its electron configuration is [Rn] 5f¹⁴ 6d⁷ 7s².
Key facts
| Atomic number | 109 |
|---|---|
| Atomic mass | 278 u |
| Category | Transition Metal |
| Period | 7 |
| Group | 9 |
| Block | d |
| Electron configuration | [Rn] 5f¹⁴ 6d⁷ 7s² |
| Electrons per shell | 2, 8, 18, 32, 32, 15, 2 |
| Electronegativity (Pauling) | --- |
| Oxidation states | +1, +3, +4, +6, +8, +9common in bold |
| State at 25 °C | --- |
| Melting point | --- |
| Boiling point | --- |
| Density | 27.5 g/cm³ |
Atomic properties
| First ionization energy | --- |
|---|---|
| Electron affinity | --- |
| Atomic radius | --- |
| Covalent radius | --- |
| Van der Waals radius | --- |
| Common ions | --- |
| Protons, neutrons, electrons | 109, 169, 109 |
Physical and thermal properties
| Molar volume | 10 cm³/mol |
|---|---|
| Heat of fusion | --- |
| Heat of vaporization | --- |
| Specific heat | --- |
| Thermal conductivity | --- |
| Thermal expansion | --- |
| Mohs hardness | --- |
| Young’s modulus | --- |
| Crystal structure | Face-centered cubic |
| Magnetic type | --- |
Identification and history
| CAS number | 54038-01-6 |
|---|---|
| Latin name | Meitnerium |
| Discovered by | Gesellschaft für Schwerionenforschung · 1982 |
| Named by | --- |
Natural isotopes
Meitnerium has no stable isotopes: every isotope is radioactive.
No visible amount of Meitnerium has ever been made: its physical properties here are theoretical estimates, not measurements.
Data checked against PubChem (NIH), IUPAC, the NIST Atomic Spectra Database and the IAEA (NUBASE and AME), the same data you see in the app.
A dash (---) means there is no reliable published measurement. The app never makes one up.
See Meitnerium in the app
Orbital diagram with Hund’s rule, emission spectrum, shell model, every isotope, a real photo, and comparison with any other element. Free, no ads, works offline.