Electron configuration

Science

Definition

Electron configuration describes the arrangement of electrons in an atom's orbitals, following the Aufbau principle, Pauli exclusion principle, and Hund's rule. It determines an element's chemical properties and its position on the periodic table.

Examples

  • Carbon's electron configuration is 1s²2s²2p², showing 4 valence electrons available for bonding
  • Sodium (1s²2s²2p⁶3s¹) easily loses its one 3s electron to form Na⁺
  • Noble gases like neon (1s²2s²2p⁶) have completely filled outer shells, making them very stable and unreactive
Key Fact

Orbital filling order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p...

Related Terms

Periodic trends Element groups Atomic models Electronegativity

Study This Concept

Practice electron configuration with free review games in these units:

AP Chemistry Unit 1: Atomic Structure and Properties Chemistry Unit 1: Matter and Atomic Structure