Cerium Electron Configuration
Interactive reference for cerium's anomalous electron configuration ([Xe] 4f¹ 5d¹ 6s²), orbital box diagram, quantum numbers, and key chemical properties of element 58.
Use the Cerium Electron Configuration
Cerium — Electron Configuration
Atomic number 58 · Lanthanide (rare earth) · Period 6, f-block · Anomalous 4f/5d filling
Aufbau Anomaly
Predicted filling would give [Xe] 4f² 6s², but cerium uses [Xe] 4f¹ 5d¹ 6s². The 4f and 5d subshells are nearly degenerate in energy at Z=58, so occupying both reduces electron repulsion. This dual occupancy enables both +3 and +4 oxidation states.
Subshell Breakdown (valence region shown explicitly)
| Subshell | Type | Electrons | Max | Notation |
|---|---|---|---|---|
| [Xe] core | shells 1–5 (1s through 5p) | 54 | 54 | [Xe] |
| 4f | f orbitals, shell n=4 | 1 | 14 | 4f¹ |
| 5d | d orbitals, shell n=5 | 1 | 10 | 5d¹ |
| 6s | s orbital, shell n=6 | 2 | 2 | 6s² |
| Total | 58 | |||
Full Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 4f¹ 5d¹ 6s²
All subshells written explicitly. 58 electrons total.
Noble-Gas Shorthand
[Xe] 4f¹ 5d¹ 6s²
[Xe] = 54-electron xenon core (1s² through 5p⁶).
Shell Fill Summary
Shell 4 can hold 32 electrons (4s + 4p + 4d + 4f). Cerium has 19: the 4f subshell just begins filling.
Summary
Cerium (Ce) has atomic number 58 and the ground-state electron configuration [Xe] 4f¹ 5d¹ 6s². Unlike most lanthanides that fill only the 4f subshell, cerium simultaneously occupies both 4f and 5d orbitals — an anomaly arising from the near-degeneracy of the 4f and 5d subshells at this point in the periodic table. This dual occupancy is directly responsible for cerium's unique ability to exhibit both +3 and +4 oxidation states. This tool provides a full subshell breakdown, noble-gas shorthand, orbital box diagram, quantum numbers, and key physical and chemical data for cerium.
How it works
- The Aufbau principle fills orbitals from lowest to highest energy following the (n + l) rule.
- Cerium's 58 electrons fill the xenon core (1s through 5p, 54 electrons) plus four valence electrons.
- The four valence electrons occupy 4f¹, 5d¹, and 6s² — with one electron in each of 4f and 5d rather than two in 4f.
- This anomaly occurs because the 4f and 5d subshells are nearly degenerate in energy at Z=58.
- The noble-gas shorthand [Xe] 4f¹ 5d¹ 6s² replaces the 54-electron xenon core with [Xe] in brackets.
- The orbital diagram and quantum-number table let you inspect each valence electron individually.
Use cases
- Quick reference for chemistry homework or exam review on lanthanide electron configurations.
- Understand the 4f¹ 5d¹ 6s² anomaly and why cerium deviates from simple Aufbau filling.
- Learn how the dual 4f/5d occupancy enables the Ce³⁺ and Ce⁴⁺ oxidation states.
- Compare cerium (Z=58) to neighboring lanthanum (Z=57) and praseodymium (Z=59).
- Teaching aid for f-block chemistry, lanthanide contraction, and periodic trends.
- Verify quantum numbers for cerium's valence electrons in bonding or spectroscopy work.
- Reference cerium's electron structure when studying catalytic converters or rare-earth chemistry.