2.2 Electron configuration

Define electron configuration

The distribution of electrons among the energy levels, sublevels, and orbitals of an atom.

Define orbital.

A region of space around the nucleus where there is a high probability of finding an electron.

Define atomic orbital.

A mathematical function describing the wave-like behaviour of an electron in an atom.

Define principal quantum number (n).

A number that indicates the main energy level or shell an electron occupies.

Define energy level (shell).

A fixed region around the nucleus where electrons with similar energies are found.

Define sublevel (subshell).

A division of an energy level consisting of orbitals with the same shape (s, p, d, f).

Define Aufbau principle.

Electrons fill orbitals of the lowest available energy first.

Define Pauli exclusion principle.

No two electrons in an atom can have the same set of four quantum numbers; an orbital can hold a maximum of two electrons with opposite spins.

Define Hund’s rule.

Electrons fill degenerate orbitals singly before pairing, with parallel spins.

Define degenerate orbitals.

Orbitals that have the same energy.

Define ground state.

The lowest energy state of an atom when all electrons are in the lowest possible energy orbitals.

Define excited state.

A higher energy state of an atom when one or more electrons occupy higher energy orbitals than normal

Define electron shell capacity rule.

The maximum number of electrons in a shell is given by 2n²

What does s orbital mean?

A spherical orbital that can hold up to two electrons.

What does p orbital mean?

A dumbbell-shaped orbital; each set contains three orbitals and can hold six electrons total.

What does d orbital mean?

A set of five orbitals with more complex shapes; can hold ten electrons total.

Define electron configuration notation.

A standard method of indicating the number of electrons in each subshell (e.g., 1s² 2s² 2p⁶).

Define electron configuration anomalies.

Exceptions where electrons occupy orbitals to achieve half-filled or fully filled d-sublevels, such as in chromium and copper.