Calculateur de Configuration Électronique Gratuit
Calculez la configuration électronique, les électrons de valence et la période à partir du numéro atomique.
Total Electrons
11
Total Electrons vs Atomic Number (Z)
Formule
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.
Exemple Résolu
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
Questions Fréquentes
What are valence electrons?
Valence electrons are the electrons in the outermost shell (highest principal quantum number). They determine chemical bonding behavior.
Why do some elements have exceptions?
Cr ([Ar]3d⁵4s¹) and Cu ([Ar]3d¹⁰4s¹) are common exceptions. Half-filled and fully filled d subshells provide extra stability.
How does electron configuration relate to the periodic table?
The periodic table is organized by electron configuration. Columns (groups) share the same number of valence electrons; rows (periods) share the same outermost shell.
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