Why an orbital can not hold more than 2 electrons?

Dear Student,

According to Pauli's Exclusion principle, no two electrons in an atom can have the same four quantum numbers. They can have three same quantum numbers in an orbital(n,m,l) but their magnetic spin cannot be the same.

The magnetic spin has only two values, +1/2 and -1/2. If a third electron enters the orbital, it will have a magnetic spin of +1/2 or -1/2, which will lead to two electrons having the same four quantum numbers in an orbital. This will be a violation of Pauli's principle.

Thus, an orbital cannot have more than 2 electrons.

Hope it helps.


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Acc. To pauli

All the Quantum number of two electron cannot be same in an same orbital three of four quantum numbers are same but spin is different. Spin no can have two values -1/2 or 1/2

So only two electrons can exist
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