Angular Momentum Quantum Number Definition

The angular momentum quantum number determines the shape of an electron orbital. p orbitals are the result of an angular momentum quantum number equal to 1.
The angular momentum quantum number determines the shape of an electron orbital. p orbitals are the result of an angular momentum quantum number equal to 1. Adisonpk / Getty Images
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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.
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Updated on February 12, 2019

The angular momentum quantum number, ℓ, is the quantum number associated with the angular momentum of an atomic electron. The angular momentum quantum number determines the shape of the electron's orbital.

Also Known As: azimuthal quantum number, second quantum number

Example: A p orbital is associated with an angular momentum quantum number equal to 1.

History

The angular momentum quantum number came from the Bohr model of the atom, as proposed by Arnold Sommerfeld. The lowest quantum number from spectroscopic analysis had an angular momentum quantum number of zero. The orbit was considered to be an oscillating charge, which appeared as a sphere in three dimensions.

Source

  • Eisberg, Robert (1974). Quantum Physics of Atoms, Molecules, Solids, Nuclei and Particles. New York: John Wiley & Sons Inc. pp. 114–117. ISBN 978-0-471-23464-7.
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Helmenstine, Anne Marie, Ph.D. "Angular Momentum Quantum Number Definition." ThoughtCo, Feb. 16, 2021, thoughtco.com/angular-momentum-quantum-number-604781. Helmenstine, Anne Marie, Ph.D. (2021, February 16). Angular Momentum Quantum Number Definition. Retrieved from https://www.thoughtco.com/angular-momentum-quantum-number-604781 Helmenstine, Anne Marie, Ph.D. "Angular Momentum Quantum Number Definition." ThoughtCo. https://www.thoughtco.com/angular-momentum-quantum-number-604781 (accessed January 10, 2025).