Pauli exclusion principle

Definition

The Pauli exclusion principle states that no two electrons in an atom can have the same set of four quantum numbers. This principle underlies the structure of electron configurations and explains the unique placement of electrons within orbitals.

5 Must Know Facts For Your Next Test

1. It is essential for understanding the arrangement of electrons in atoms.
2. Each electron in an atom must have a unique set of quantum numbers: $n$, $l$, $m_l$, and $m_s$.
3. The principle explains why electrons fill orbitals in a specific order, following Hund's rule and the Aufbau principle.
4. It is crucial for explaining atomic behavior and properties due to electron configurations.
5. The principle is named after Wolfgang Pauli, who formulated it in 1925.

Review Questions

• What does the Pauli exclusion principle state about electron quantum numbers?
• How does the Pauli exclusion principle affect electron configurations?
• Who formulated the Pauli exclusion principle and when?

Related terms

Quantum Numbers:

Set of four numbers ($n$, $l$, $m_l$, and $m_s$) that describe an electron's position and energy state within an atom.

Hund's Rule:

States that electrons will fill degenerate orbitals singly before pairing up, minimizing repulsion within an atom.

Aufbau Principle:

Describes the methodical filling of atomic orbitals with electrons from lowest to highest energy levels.