i. Principal Quantum Number (n): It defines the shell. It determines the size and energy of the orbit. The values of n are: n = 1, 2, 3, ……
ii. Azimuthal Quantum Number (l): It defines the shape of the orbital. For the given value of "n", the possible values of "l" are l = 0, 1, 2, 3, …. Each orbital is represented by the letters s, p, d, f.
iii. Magnetic Quantum Number (ml): It gives the spatial orientation of the orbital. For any value of l,ml can have (2l + 1) values ranging from –l to +
iv. Spin Quantum Number(ms): It refers to the spin of the electron. The value of spin quantum no are +1/2 and -1/2.