Pauli exclusion principle
States that no two electrons in the same atom can have identical values for all four quantum numbers.
What is Pauli exclusion principle?
A set of numbers used to describe the properties of electrons in atoms, including energy level, shape of orbital, orientation of orbital, and spin of electron.
Key formula / rule: Maximum electrons in an orbital
Key points
- Understand the statement of the Pauli Exclusion Principle.
- Relate the principle to the four quantum numbers.
- Determine the maximum number of electrons in an orbital based on the principle.
- Explain its role in electron configuration and atomic structure.
Common exam trap
Confusing the principle with the maximum number of electrons in a shell (2n2) or subshell (2(2l+1)).
Definitions
- Term
Quantum Numbers
- Meaning
A set of numbers used to describe the properties of electrons in atoms, including energy level, shape of orbital, orientation of orbital, and spin of electron.
- Term
Spin Quantum Number (ms)
- Meaning
Describes the intrinsic angular momentum of an electron, which can have one of two values: +1/2 (spin up) or -1/2 (spin down).
Learning objectives
Understand the statement of the Pauli Exclusion Principle.
Relate the principle to the four quantum numbers.
Determine the maximum number of electrons in an orbital based on the principle.
Explain its role in electron configuration and atomic structure.
Formulae
- Name
Maximum electrons in an orbital
- Note
Based on Pauli Exclusion Principle, where two electrons with opposite spins (+1/2 and -1/2) can occupy a single orbital.
- Expression
2
Prerequisites
Quantum Numbers (n, l, ml, ms)
Atomic Orbitals
Electron Spin
Common mistakes
Confusing the principle with the maximum number of electrons in a shell (2n2) or subshell (2(2l+1)).
Assuming that electrons in different orbitals can have the same quantum numbers without considering spin.
Applying the principle to systems with identical bosons.
Keywords
Pauli Exclusion Principle
Quantum Numbers
Electron Configuration
Atomic Orbitals
Spin Quantum Number
Quantum Mechanics
Periodic Table
Practice preview
Which set of quantum numbers is directly constrained by the Pauli exclusion principle when considering two electrons in the same orbital?…
easy
Which of the following electron configurations for an atom violates the Pauli exclusion principle?…
medium
Why do two electrons occupying the same atomic orbital have opposite spins?…
medium