Quantum numbers are a set of values that describes the state of an electron including its distance from the nucleus, the orientation and type of orbital where it is likely to be found, and its spin.
The Pauli exclusion principle states that no two electrons in an atom can have the same set of quantum numbers.
The principle quantum number (n) is the number of the electron's shell.
n = 1, 2, 3, 4,.......
The angular momentum quantum number (l) .
The orbital angular momentum quantum number l determines the shape of an orbital, and therefore the angular distribution. The number of angular nodes is equal to the value of the angular momentum quantum number l.
l= 0, 1, 2, 3, 4, (n-1).
The magnetic quantum number (ml) is the orientation of the orbital.
The magnetic quantum number mlml determines the number of orbitals and their orientation within a subshell. Consequently, its value depends on the orbital angular momentum quantum number l.
The spin projection quantum number (ms) is the spin of the electron (either -½ or ½).
Unlike nn, ll, and mlml, the electron spin quantum number msms does not depend on another quantum number. It designates the direction of the electron spin and may have a spin of +1/2, represented by↑, or –1/2, represented by ↓.