Enter an element's symbol, name, or atomic number — plus an optional charge for ions — and the Electron Configuration Calculator returns the full electron configuration, condensed (noble gas) form, valence electrons, and a shell-by-shell breakdown, so you can see exactly how electrons are arranged without memorizing Aufbau rules.
Element
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Full Electron Configuration
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Condensed Configuration
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Valence Electrons
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Atomic Number
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Total Electrons
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Electron configuration describes how electrons are distributed among the atomic orbitals of an atom. It shows the arrangement of electrons in shells and subshells, following specific rules like the Aufbau principle, Hund's rule, and Pauli exclusion principle.
The shorthand or condensed method uses noble gas notation. Start with the nearest noble gas with fewer electrons, write it in brackets, then continue with the remaining electron configuration. For example, sodium (Na) is [Ne] 3s¹ instead of 1s² 2s² 2p⁶ 3s¹.
Valence electrons are the electrons in the outermost shell of an atom that participate in chemical bonding. They determine an element's chemical properties and reactivity. For main group elements, valence electrons are in the highest energy s and p orbitals.
Carbon has 4 valence electrons. Its electron configuration is 1s² 2s² 2p², and the valence electrons are the 4 electrons in the outer shell (2s² 2p²). This is why carbon forms 4 covalent bonds in most compounds.
For cations (positive ions), remove electrons from the highest energy orbitals first. For transition metals, remove s electrons before d electrons. For anions (negative ions), add electrons to the next available orbital following normal filling order.
This electron configuration belongs to sulfur (S), which has atomic number 16. The configuration shows 16 electrons total: 2 + 2 + 6 + 2 + 4 = 16. Sulfur has 6 valence electrons in its outer shell (3s² 3p⁴).
The three main rules are: 1) Aufbau principle - electrons fill orbitals from lowest to highest energy, 2) Hund's rule - electrons occupy orbitals singly before pairing up, and 3) Pauli exclusion principle - no two electrons can have identical quantum numbers.
Oxygen has 6 valence electrons. Its electron configuration is 1s² 2s² 2p⁴, and the valence electrons are in the outer shell (2s² 2p⁴). This is why oxygen typically forms 2 bonds to complete its octet.