Mendelevium (Md): Electron Configuration, Properties and Uses
Mendelevium (Md): Electron Configuration, Properties and Uses
Electron configuration [Rn] 7s2 5f13 · f-block, actinide series · period 7 · Ar [258]
Mendelevium data
- Atomic number
- 101
- Relative atomic mass
- [258]
- Group
- – (actinide series)
- Period
- 7
- Block
- f
- Category
- Actinide
- Electron configuration
- [Rn] 7s2 5f13
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f13
- Electrons per shell
- 2, 8, 18, 32, 31, 8, 2 (K L M N O P Q)
- Valence electrons
- 2 (in the outer shell)
- Electronegativity (Pauling)
- 1.3
- First ionisation energy
- 6.58 eV
- Atomic radius (van der Waals)
- no data
- State at room temperature
- Solid
- Melting point
- 827 °C
- Boiling point
- no data
- Density
- no data
- Common oxidation states
- +3, +2
- Discovered
- 1955
Source: PubChem (NIH, accessed 13 Nov 2026); atomic mass: IUPAC standard atomic weight.
Electron shell diagram
K 2 · L 8 · M 18 · N 32 · O 31 · P 8 · Q 2
Orbital diagram (outer electrons)
About mendelevium
Mendelevium, symbol Md, is element number 101 in the periodic table. It belongs to the actinide series in period 7 (f-block), usually shown below the main table. The element was discovered in 1955. It is named after Dmitri Mendeleev, who devised the periodic table. Mendelevium is a solid at room temperature, melting at 827 °C.
Mendelevium electron configuration
The electron configuration of mendelevium is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f13, or in short [Rn] 7s2 5f13. Its electrons occupy 7 shells: K = 2, L = 8, M = 18, N = 32, O = 31, P = 8, Q = 2. As an actinide, mendelevium fills the 5f subshell. Its outer 7s subshell holds 2 electrons; valence electrons for this series are not assigned by the usual group rule. When it forms cations, electrons leave the outermost subshell first: Md3+ = [Rn] 5f12.
Filling order: 1s2(2) → 2s2(4) → 2p6(10) → 3s2(12) → 3p6(18) → 4s2(20) → 3d10(30) → 4p6(36) → 5s2(38) → 4d10(48) → 5p6(54) → 6s2(56) → 4f14(70) → 5d10(80) → 6p6(86) → 7s2(88) → 5f13(101)
Uses of mendelevium
Mendelevium is used for research only; it was the first element made and detected one atom at a time.
Safety
Mendelevium is radioactive. Using, storing or transporting radioactive material requires a licence from the national regulator (BAPETEN in Indonesia). Always read the safety data sheet (SDS) before working with a chemical.
Other actinides
Frequently asked questions
What is the electron configuration of mendelevium?
The electron configuration of mendelevium (Md, atomic number 101) is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f13, or [Rn] 7s2 5f13 in short. By shell: 2, 8, 18, 32, 31, 8, 2.
How many valence electrons does mendelevium have?
Mendelevium has 2 electrons in its outer shell. For lanthanides and actinides, valence electrons are not assigned by the usual group rule.
Which group and period is mendelevium in?
Mendelevium is in the actinide series, period 7, f-block.
What is the atomic mass of mendelevium?
Mendelevium has no stable isotope, so the mass number of its longest-lived isotope, [258], is given.
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