Aufbau Principle

Excited state

Ground state

Heisenberg Uncertainty Principle

Hund's Rule

Ionization energy

Pauli Exclusion Principle

Electrons occupy the lowest energy level available

The state of an atom when one or more of its electrons have been promoted to higher energy levels

The state of an atom when all of its elements are in their lowest available energy levels

It is not possible to ascertain both the position and momentum of an electron in an atom simultaneously

When two or more orbitals of equal energy are available to electrons, the electrons will occupy them singly before filling them in pairs

The minimum energy required to remove the most loosely bound electron from an isolated atom of that element

No more than two electrons can occupy an orbital, and this they can only do if they have opposite spin