Element 109 · Unknown properties
Meitnerium (Mt) — Element 109
Lise Meitner
Meitnerium (Mt) is a chemical element with unknown bulk chemical properties in Period 7, Group 9 of the periodic table with atomic number 109, standard atomic weight [278] u, and ground-state electron configuration [Rn] 5f¹⁴ 6d⁷ 7s². At standard temperature and pressure it is classified as a short-lived synthetic nuclide with 9 valence electrons.
Research only
What are the atomic properties and physical constants of Meitnerium?
Reference constants compiled from IUPAC standard atomic weights, the NIST Atomic Spectra Database, and the CRC Handbook.
- Atomic number (Z)
- 109
- Standard atomic mass
- [278] u
- Chemical family
- Unknown properties
- Ground-state configuration
- [Rn] 5f¹⁴ 6d⁷ 7s²
- Electrons per shell
- 2, 8, 18, 32, 32, 15, 2
- Valence electrons
- 9
- Common ion charges / oxidation states
- —
- Phase at STP
- Synthetic
- Pauling electronegativity
- —
- First ionization energy
- —
- Atomic radius
- —
- Melting point
- —
- Boiling point
- —
- Discovery year
- 1982
- Table coordinate
- Period 7, Group 9
- Radioactivity
- Radioactive (no stable isotopes)
How are electrons arranged across Meitnerium’s shells?
A neutral Meitnerium atom contains 109 electrons distributed across 7 occupied principal energy shells ([Rn] 5f¹⁴ 6d⁷ 7s²). The table below compares Meitnerium’s shell occupancy against each shell’s theoretical 2n² capacity.
| Principal Shell (n) | Spectroscopic Letter | Electrons in Mt | Max Shell Capacity (2n²) |
|---|---|---|---|
| n = 1 | K | 2 e⁻ | 2 e⁻ |
| n = 2 | L | 8 e⁻ | 8 e⁻ |
| n = 3 | M | 18 e⁻ | 18 e⁻ |
| n = 4 | N | 32 e⁻ | 32 e⁻ |
| n = 5 | O | 32 e⁻ | 50 e⁻ |
| n = 6 | P | 15 e⁻ | 72 e⁻ |
| n = 7 | Q | 2 e⁻ | 98 e⁻ |
Frequently Asked Questions about Meitnerium (Mt)
What is the atomic mass and atomic number of Meitnerium (Mt)?
Meitnerium (Mt) has atomic number Z = 109 (109 protons in its nucleus) and an IUPAC standard atomic weight of [278] u. It sits in Period 7, Group 9 and is classified as an unknown properties.
What is the ground-state electron configuration of Meitnerium?
The neutral ground-state electron configuration of Meitnerium (Z = 109) is [Rn] 5f¹⁴ 6d⁷ 7s². Across its 7 occupied principal shells (n = 1 to n = 7), the electrons per shell are 2, 8, 18, 32, 32, 15, 2, with 9 valence electrons participating in bonding.
What are the common ion charges and electronegativity of Meitnerium?
Meitnerium has no common simple monatomic ion charges under standard classroom conditions. Its Pauling electronegativity is — and its first ionization energy is —.
When was Meitnerium discovered and what is it used for?
Meitnerium was discovered in 1982 (Lise Meitner). Research only
How does Meitnerium compare to neighboring elements?
Other unknown properties elements: