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CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Electron configuration

A list of which subshells an atom's or ion's electrons occupy, with the count as a superscript. The ground-state configuration follows aufbau order, the Pauli principle and Hund's rule (with the Cr and Cu exceptions).

Phosphorus: 1s2 2s2 2p6 3s2 3p31s^2\,2s^2\,2p^6\,3s^2\,3p^3.

Example

Phosphorus (Z=15Z = 15) is 1s2 2s2 2p6 3s2 3p31s^2\,2s^2\,2p^6\,3s^2\,3p^3, or [Ne] 3s2 3p3[\mathrm{Ne}]\,3s^2\,3p^3: the superscripts add to 15, and the three 3p3p electrons are unpaired.

See alsoAufbau principleNoble-gas configurationOrbital diagramSubshell