Spin Quantum Number Definition

Chemistry Glossary Definition of Spin Quantum Number

The spin quantum number describes the shape and energy of electron orbitals.
The spin quantum number describes the shape and energy of electron orbitals. RICHARD KAIL / Getty Images

The spin quantum number is the fourth quantum number, denoted by s or ms. The spin quantum number indicates the orientation of the intrinsic angular momentum of an electron in an atom. It describes the quantum state of an electron, including its energy, orbital shape, and orbital orientation.

The only possible values of a spin quantum number are +½ or -½ (sometimes referred to as 'spin up' and 'spin down').

The value of spin is a quantum state, not something so easily understood as the direction in which an electron spins!

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Helmenstine, Anne Marie, Ph.D. "Spin Quantum Number Definition." ThoughtCo, Sep. 13, 2017, thoughtco.com/definition-of-spin-quantum-number-604656. Helmenstine, Anne Marie, Ph.D. (2017, September 13). Spin Quantum Number Definition. Retrieved from https://www.thoughtco.com/definition-of-spin-quantum-number-604656 Helmenstine, Anne Marie, Ph.D. "Spin Quantum Number Definition." ThoughtCo. https://www.thoughtco.com/definition-of-spin-quantum-number-604656 (accessed May 22, 2018).