Nobelium (No): Electron Configuration and Properties
Nobelium (No): Electron Configuration and Properties
Electron configuration [Rn] 7s2 5f14 · f-block, actinide series · period 7 · Ar [259]
Nobelium data
- Atomic number
- 102
- Relative atomic mass
- [259]
- Group
- – (actinide series)
- Period
- 7
- Block
- f
- Category
- Actinide
- Electron configuration
- [Rn] 7s2 5f14
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14
- Electrons per shell
- 2, 8, 18, 32, 32, 8, 2 (K L M N O P Q)
- Valence electrons
- 2 (in the outer shell)
- Electronegativity (Pauling)
- 1.3
- First ionisation energy
- 6.65 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
- 1957
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 32 · P 8 · Q 2
Orbital diagram (outer electrons)
About nobelium
Nobelium is a chemical element with the symbol No and atomic number 102. It belongs to the actinide series in period 7 (f-block), usually shown below the main table. Nobelium was first discovered in 1957. It is named after Alfred Nobel. Nobelium is a solid at room temperature, melting at 827 °C.
Nobelium electron configuration
The electron configuration of nobelium is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14, or in short [Rn] 7s2 5f14. Its electrons occupy 7 shells: K = 2, L = 8, M = 18, N = 32, O = 32, P = 8, Q = 2. As an actinide, nobelium 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: No3+ = [Rn] 5f13.
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) → 5f14(102)
Uses of nobelium
Nobelium has no practical use outside research, because it can only be made a few atoms at a time in particle accelerators.
Safety
Nobelium 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 nobelium?
The electron configuration of nobelium (No, atomic number 102) is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14, or [Rn] 7s2 5f14 in short. By shell: 2, 8, 18, 32, 32, 8, 2.
How many valence electrons does nobelium have?
Nobelium 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 nobelium in?
Nobelium is in the actinide series, period 7, f-block.
What is the atomic mass of nobelium?
Nobelium has no stable isotope, so the mass number of its longest-lived isotope, [259], is given.
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