The first quantum number, called the principal quantum number (n), refers to the size of the electron cloud and the energy of an electron. The range of the n value goes from one to the number of the shell that contains the outermost electron.
There are four quantum numbers that are used to describe each electron in an atom. The first three numbers specify the orbital of the electron, and the fourth number describes the spin of the electron in that orbital.
The second quantum number is the angular momentum number and specifies the shape of the orbital by dividing the shell into subshells. The third quantum number is the magnetic quantum number and describes the orientation of the orbital. The fourth quantum number can take two possible values to describe the spin of the electron, sometimes referred to as up and down.