explain pauli's exclusion principle
Pauli Exclusion Principle
No two electrons in an atom can have the same set of all the four quantum numbers.
Two electrons can have the same value of three quantum numbers n, l, and me, but must have the opposite spin quantum number (s).
The maximum number of electrons in the shell with the principal quantum number n is equal to 2n2.
For example
In an orbital diagram, an electron is represented by an up arrow (↑) indicating a positive spin, or a down arrow (↓) indicating a negative spin.
And it can not be represented by both the arrows on the same side.