Free Electron Configuration Calculator
Calculate key electron configuration properties including the number of electrons in each shell, valence electrons, and core electrons from the atomic number.
Total Electrons
11
Total Electrons vs Atomic Number (Z)
Electron Configuration
How It Works
Electrons fill orbitals following three rules: 1. Aufbau Principle: Fill lowest energy orbitals first (1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, ...) 2. Pauli Exclusion: Each orbital holds at most 2 electrons with opposite spins 3. Hund's Rule: Within a subshell, one electron goes in each orbital before pairing
The order of filling follows the diagonal rule or is memorized from periodic table blocks.
Example Calculation
Find the electron configuration of sodium (Z = 11).
- 01Z = 11, so 11 electrons to place
- 021s² (2 electrons, 9 remaining)
- 032s² (2 electrons, 7 remaining)
- 042p⁶ (6 electrons, 1 remaining)
- 053s¹ (1 electron, 0 remaining)
- 06Configuration: 1s² 2s² 2p⁶ 3s¹
- 07Noble gas notation: [Ne] 3s¹
- 08Valence electrons: 1
Frequently Asked Questions
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