How can I tell how many electrons can fit in a subshell?

When figuring the electron configuration for an element, how do you know how many electrons go in each subshell(orbital)?

azimuthal quantum number* (ell)
magnetic quantum number* (mell)
A subshell is a set of electrons that all have the same value of ell (azimuthal quantum number). You can think of ell as a label for a group of orbitals that have related shapes. A subshell with ell=0 is called an s subshell and contains spherical orbitals; a subshell with ell=1 is called a p subshell and contains dumbbell shaped orbitals; a subshell with ell=2 is called a d subshell and contains (mainly) orbitals that look like 4-leafed clovers.

The number of possible orbitals in a subshell is determined by the number of possible mell values for the subshell. Think of mell as a label for individual orbitals within the subshell. For every mell value that is allowed, there is one orbital in the subshell.

Allowed values of mell are integers between -ell to +ell, including zero.

The number of possible mell values determines the number of orbitals in a subshell.

ell possible values of mell number of orbitals in this subshell
0 0 1
1 -1, 0, +1 3
2 -2, -1, 0, +1, +2 5
3 -3, -2, -1, 0, +1, +2, +3 7

Each orbital can hold a maximum of two electrons, so the maximum number of electrons you can put into the subshells are 2, 6, 10, and 14 for s, p, d, and f subshells, respectively.

Author: Fred Senese

General Chemistry Online! How can I tell how many electrons can fit in a subshell?

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