Actinides
Mendelevium
A synthetic element named for the periodic table's creator.
Atomic #101Mass[258]Blockf-blockPeriod7Group—
Md101 · [258]
3D Atom Explorer
Inside the Mendelevium atom
Switch between Bohr and Quantum Cloud modes to compare a simple teaching model with a more realistic probability-based view, and follow the guided tour to explore the Mendelevium atom step by step.
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Electron configuration
[Rn] 5f13 7s2
A neutral Mendelevium atom has 101 electrons (equal to its proton count). Choosing a different isotope above changes only the neutron count.
Shell distribution
Shell 12 e⁻Shell 28 e⁻Shell 318 e⁻Shell 432 e⁻Shell 531 e⁻Shell 68 e⁻Shell 72 e⁻
Electrons fill inner shells before outer ones; the outermost (valence) shell drives the element's chemistry.
Properties
Physical & atomic properties
- State (room temp)
- Unknown
- Melting point
- 1100 K (827 °C)
- Boiling point
- —
- Density
- —
- Electronegativity
- 1.3 Pauling
- Atomic radius
- —
- 1st ionization energy
- 635 kJ/mol
- Category
- Actinides
History
Discovery & naming
- Discovered
- 1955
- Discovered by
- Albert Ghiorso and colleagues
- Origin of name
- Chemist Dmitri Mendeleev.
Notable uses
Scientific research only.
Cosmic origin
Where Mendelevium comes from
Human synthesis
Synthetic. Beyond fermium, elements must be assembled by firing nuclei at each other.
Simplified origin map — many elements form through more than one astrophysical pathway.
Summary
- Atomic number
- 101
- Atomic mass
- [258]
- Category
- Actinides
- Group · Period
- — · 7
- Block
- f-block
- Shells
- 2 · 8 · 18 · 32 · 31 · 8 · 2