Exclusion Principle

principle that states that two identical particles with spins equal to half an odd integer cannot be in the same quantum state (Physics)

Exclusion principle may refer to:The Exclusion principle, an epistemological principleIn economics, the exclusion principle states "the owner of a private good may exclude others from use unless they pay."The Pauli exclusion principle, a quantum mechanical principle
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Noun
1. no two electrons or protons or neutrons in a given system can be in states characterized by the same set of quantum numbers
(synonym) Pauli exclusion principle
(hypernym) law, law of nature

A fundamental principle of A fundamental principle of quantum theory which states that no two fermions in a single system can exist in the same quantum state. The principle describes the physical processes which lead to the structure of atoms. It is also essential in describing the conditions under which degenerate matter exists. Hence it explains how white dwarfs and neutron stars support themselves against the downward pull of gravity.

No two electrons in an atom can have the same set of 4 quantum numbers. Because the n,, and m quantum numbers address a particular orbital, and because the ms quantum number has only two possible values, the Pauli principle says that a maximum of two electrons can occupy an atomic orbital- and these electrons must have opposite spins.