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Question
State and explain Pauli's exclusion principle.
Solution
Pauli’s exclusion principle states that “No two electrons in an atom can have the same set of values of all four quantum numbers”.
Illustration: H(Z = 1) 1s1.
One electron is present in hydrogen atom, the four quantum numbers are n = 1, l = 0, m = 0 and s = `+1/2`. For helium Z = 2. He: 1s2. In this one electron has the quantum number same as that of hydrogen, n = 1, l = 0, m = 0 and s = `+1/2` For other electron, fourth quantum number is different, i.e. n = 1, l = 0, m = 0 and s = `-1/2`.
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