Recognised as Chemical element
Meitnerium
- Mt
- Z = 109
- element of unknown category
- No stable isotope
Meitnerium (Mt) is element 109, an element of unknown category in period 7 and group 9. Its most stable isotope has mass number 278. Weights follow IUPAC standard atomic weights, 2021 revision.
Identity
SymbolMt
Mass number of the most stable isotope278this element has no stable isotope
Mass in kilograms4.6162986 × 10^-25
Categoryelement of unknown category
Group9
Period7
Blockd-block
Electrons in a neutral atom109
Neutrons in the most common isotope169≈
Electron configuration
Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d⁷ 7s²predicted by the Madelung rule; no ground state has been measured
Noble gas shorthand[Rn] 5f¹⁴ 6d⁷ 7s²
Electrons per shell2, 8, 18, 32, 32, 15, 2K, L, M and outward
Electrons in the outer shell2
Unpaired electrons3Hund's rule; unpaired electrons make the free atom paramagnetic
Madelung ruleAssumeda prediction, not a measurement
Quantities
Molar mass278 g/mol
Mass of one mole278 grams
Atoms in one gram2.1662377 × 10^21
Mass of one atom4.6162986 × 10^-22 g
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