Significance of three quantum numbers in predicting the positions of an electron in an orbit. 

1) Principal quantum number (n) : 

The principal quantum number explains about the size and energy of shells (or) orbitals. It is denoted by n. 

As ‘n’ increases, the orbitals become larger and the electrons in those orbitals are farther from the nucleus.

It takes values 1, 2, 3, 4, ……………. for that the shells are represented by letters K, L, M, N, ……….

The number of electrons in a shell is limited to 2n²

2) The Angular – momentum quantum number (l) : 

The angular momentum quantum number defines the shape of the orbital occupied by the electron and the orbital angular momentum of the electron, is in motion.

l takes values from 0 to n – 1 for these values the orbitals are designated by letters s, p, d, f, ………….. etc. 

l also governs the degree with which the electron is attached to nucleus. The larger the value of l, the smaller is the bond with which it is maintained with the nucleus.

3) Magnetic orbital quantum number (m ) : 

The orientation of orbital with external magnetic field determines magnetic orbital quantum number. 

m_| has integer values between – l and l including zero. 

The number of values for m, are 2l + l, which give the number of orbitals per sub-shell. The maximum number of electrons in orbitals in the sub-shell is 2 (2l + l).