the Pauli exclusion principle forbids

Fermions cannot occupy the same quantum state

Electrons in the same orbital must have different spin quantum numbers (ms), which can only be +1/2 or -1/2. This difference in spin states is essential for the stability of atoms and the formation of chemical bonds.

Example

In a helium atom, both electrons must have different ms values (+1/2 and -1/2) even though they share the same n, ℓ, and mℓ values.

Remember this

Understanding the Pauli exclusion principle is vital for explaining atomic and molecular structures, influencing chemical reactions, and the properties of materials.

Text adapted from Wikipedia, licensed under CC BY-SA 4.0.

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