What do the letters s, p, d, and f in the orbital names stand for?

You might expect that the 's' stands for 'spherical' and 'p' stands for 'polar' because these imply the shapes of the s and p orbitals, but unfortunately, the letter designations have nothing to do with the orbital shapes.

Spectroscopists associated transitions involving energy levels with different ell values with different groups of lines in the line spectra of the alkali metals. The line groups were called sharp, principal, diffuse, and fundamental. When the angular momentum quantum number was used to describe and explain these groups of lines, s became an abbreviation for = 0, p meant = 1, d meant = 2, and f meant = 3. For consistency, higher values of the angular momentum quantum numbers are designated alphabetically (g means = 4, h means = 5, and so on).

Author: Fred Senese senese@antoine.frostburg.edu

General Chemistry Online! What do the letters s, p, d, and f in the orbital names stand for?