Second Quantum Number Definition

The second quantum number describes the shape of an electron's orbit.
The second quantum number describes the shape of an electron's orbit. PASIEKA / Getty Images
by Anne Marie Helmenstine, Ph.D.
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.
Updated July 26, 2017

Second Quantum Number Definition: The second quantum number, ℓ, is the quantum number associated with the angular momentum of an atomic electron. The second quantum number determines the shape of the electron's orbital.

Also Known As: azimuthal quantum number, angular momentum quantum number

Examples: A p orbital is associated with a second quantum number equal to 1.