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Home » Class 11 » Chemistry » Pauli Exclusion Principle

Pauli Exclusion Principle

Last Updated on May 3, 2020 By Mrs Shilpi Nagpal Leave a Comment

Wolfgang Pauli a German physicist in 1925 put forward a principle known after his name as Pauli exclusion principle.

No two electrons in an atom can have the same set of four quantum number.

In an atom ,any two electrons may have the same values for any of the three quantum numbers but the 4th must be different.

Any particular orbital is described by three quantum numbers i.e. n, l and m.

For Ex: 3 s orbital has n=3 , l=0 and m=0.

Since for each value of m, there are two values of the spin quantum number i.e. + ½ and  – ½  therefore 3s orbital can have two electrons, one with quantum number n=3 , l=0, m=0 and s= + ½  and other with quantum number, n=3 , l=0, m=0 and s= – ½ .

Pauli Exclusion principle

 

An orbital can have a maximum two electrons and these have opposite Spins.

Number of sub shells in nth shell = n.

Number of orbitals in a sub shell = 2l + 1

Maximum number of electrons in a sub shell=2(2l +1)

Number of orbitals in nth shells = n2

Maximum number of electrons in nth shell = 2n2

Filed Under: Chemistry, Class 11, Structure Of Atom Tagged With: Pauli exclusion principle

About Mrs Shilpi Nagpal

Author of this website, Mrs Shilpi Nagpal is MSc (Hons, Chemistry) and BSc (Hons, Chemistry) from Delhi University, B.Ed (I. P. University) and has many years of experience in teaching. She has started this educational website with the mindset of spreading Free Education to everyone.

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