Electron configuration

M_s

The spin quantum number, can have 2 values: +1/2 and -1/2. + is up and - is down.

Pauli Exclusion Principle

No two electrons can have the same four quantum numbers. Results in a specific orbital having ONLY 2 electrons one with a + spin and - spin.

Effective nuclear charge (Z_eff)

The net charge experienced by an electron in a multi-electron atom, accounting for shielding by other electrons. It is calculated as the Z_actual - Electron Shielding = Z_eff

Z_eff and Energy of orbitals graph

Electron configuration

A description of which orbitals in an atom are occupied by electrons

Aufbau Principle

The principle that electrons fill atomic orbitals starting from the lowest energy level to the highest. This is used to determine the electron configuration of an atom.

Ground-state electron configuration

The electron configuration of an atom in its lowest energy state, showing the distribution of electrons among the atomic orbitals.

Degenerate

orbitals that have the same energy level.

Hund’s rule

if two or more degenerate orbitals are available one electron goes in each until all are half full