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
By
Anne Marie Helmenstine, Ph.D.
Anne Marie Helmenstine, Ph.D.
Chemistry Expert
  • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
  • B.A., Physics and Mathematics, Hastings College
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
Learn about our Editorial Process
Updated on December 07, 2018

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!

Sources

  • Atkins, P.; de Paula, J. (2006). Physical Chemistry (8th ed.). W. H. Freeman. ISBN 0-7167-8759-8.
  • Bertolotti, Mario (2004). The History of the Laser. CRC Press. pp. 150–153.
  • Merzbacher, E. (1998). Quantum Mechanics (3rd ed.). John Wiley. p.430-1 ISBN 0-471-88702-1.
Format
mla apa chicago
Your Citation
Helmenstine, Anne Marie, Ph.D. "Spin Quantum Number Definition." ThoughtCo, Aug. 27, 2020, thoughtco.com/definition-of-spin-quantum-number-604656. Helmenstine, Anne Marie, Ph.D. (2020, August 27). 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 June 9, 2023).