Question

pauli's exclusion principle

Answer 1

Pauli's exclusion principle is" the quantum mechanical principle that states that two identical fermions( partical with half integer spin) cannot occupy the same quantum state simultaneously."

Answer 2

Hey !

Electrons which have the same spin strongly repel each other and tend to occupy different regions of space. This is a result of a fundamental law of nature known as the Pauli's exclusion principle.

Pauli's principal may be stated as no two electrons in an atom can have the same set of values for all the four quantum numbers.

This means that two electrons in an atom may have the same n, same L and same m but differ in spin quantum number. In an orbital if one electron has clockwise spin, the other has anticlockwise spin. It follows that an orbital can hold a maximum of two electrons with opposite spins.

Example :- Helium atom has two electrons in its 1s orbital. Quantum numbers of first electron are :- n = 1 ,L = 0 and S = +1/2. Quantum number for second electron are :- n = 1, L = 0, m = 0 , S = -1/2. The two electrons have the same value for n, same value for L and same value for m but differ in s.

Good luck !