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Quantum Numbers

All electrons present in an atom have specific addresses or attributes by which each electron can be referred to. The four quantum numbers are the ones with which we can describe each and every electron that is present in an atom. One of the quantum numbers describes the shape or the most probable area around the nucleus where we can find the particular electrons of interest. This wave function of an electron is called an orbital.

Principal quantum number (n). The principal quantum number denotes the energy level of electrons. The larger the principal quantum number is, the larger the energy. The smaller the principal quantum number is, the lower the energy. The shells are often named K, L, M, N, . . ., which correspond to the principal quantum numbers 1, 2, 3, 4, . . ., respectively.





N . . .





4 . . .

Angular momentum quantum number (l).
Angular momentum quantum number (azimuthal quantum number) denotes the shape of the orbital. The values range from 0 to n – 1, where n stands for the principal quantum number. If an electron has a principal quantum number of 4, the values of angular momentum quantum numbers are 0, 1, 2, and 3. The angular momentum quantum numbers correspond to different subshells. An angular momentum quantum number 0 corresponds to s subshell, 1 to p subshell, 2 to d subshell, 3 to f subshell, and so on. For instance, 3d denotes a subshell with quantum numbers n = 3 and l =2





f . . .





3 . . .



Magnetic quantum number (ml). Magnetic quantum numbers define the different spatial orientations of the orbitals. The values from l to +l. For example, let's say the value of l is 1. So the magnetic quantum numbers will be 1, 0, and +1. The l value corresponds to p sublevel and the three magnetic quantum numbers correspond to the three atomic orbitals in the p subshell.
Spin quantum number (ms). Spin quantum number has to do with the spin orientations of an electron. The two possible spins are denoted by the spin quantum numbers +1/2 and 1/2.

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