1.3 Atomic Structure: Electron Configurations

Ground-state electron configuration

The lowest-energy arrangement of an atom's electrons in orbitals.

Aufbau principle

The rule stating that the lowest-energy orbitals fill up first.

Pauli exclusion principle

The rule that states two electrons can occupy an orbital only if they have opposite spins.

Hund's rule

The rule stating that electrons occupy degenerate orbitals singly with parallel spins before pairing up.

1s configuration

The ground-state configuration for hydrogen, indicating one electron in the lowest-energy 1s orbital.

Superscript in electron configuration

Indicates the number of electrons in a particular orbital.

Orbital energy levels

The order of energy in which electrons occupy orbitals, with lower energy levels filled first.

Electron spin

The property of electrons that can be oriented as either 'up' (↑) or 'down' (↓).