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Meitnerium

Element 109 · Transition metal

Specimen

Atomic number
109
Atomic mass
[277]
State at room temperature
Solid
Melting point
Unknown
Boiling point
Unknown
Density
Unknown
Discovered
1982

Mass number of the longest-lived isotope, from IUPAC.1 Other physical data from PubChem.2

Can I eat it?

In food and water
Never made in amounts you could eat. Fewer than 10 atoms of meitnerium have ever been made. 3

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The atom

Mt
ShellElectrons
1 (K) 2
2 (L) 8
3 (M) 18
4 (N) 32
5 (O) 32
6 (P) 15
7 (Q) outermost 2
Total109

Configuration [Rn] 5f¹⁴ 6d⁷ 7s²

5f ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓
6d ↑ ↓ ↑ ↓ ↑ ↑ ↑
7s ↑ ↓
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 109 protons. The outermost shell is shown in red. Electrons do not travel on rings: they fill orbitals, regions where an electron is likely to be found. The boxes are those orbitals for the electrons outside the Rn core, with one arrow per electron. This configuration is a prediction; it has not been measured.

Related elements

Group 9
Co Cobalt Rh Rhodium Ir Iridium

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Sources

  1. 1

    IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW), 2024. Radioactive Elements .

    Mass number and half-life of the longest-lived isotope of the 34 elements with no standard atomic weight.

  2. 2

    National Center for Biotechnology Information (PubChem), 2026. Periodic Table of Elements .

    Electron configuration, melting and boiling points, density and discovery year for all 118 elements.

  3. 3

    Royal Society of Chemistry, Periodic Table, 2026. Meitnerium - Element information, properties and uses .

    Reference page; its Biological role and Natural abundance sections are quoted.

    • Fewer than 10 atoms of meitnerium have ever been made, and it will probably never be isolated in observable quantities.