Answer:
- Pauli's exclusion principle
Explanation:
You can read this principle in any chemistry or physics textbook that deals with quantum numbers. It states that two electrons of an atom cannot have the same set of four quantum numbers.
As result:
- Any orbital can have a maximum of two electrons, and
- Two electrons in a same orbital have opposite spins: one will have +1/2 and the other will have -1/2.
Remember, that the quantum numbers are the numbers that identify the electrons in an atom.
- n is the principal quantum number, and can have positive integer vaules: 1, 2, 3, 4, 5, 6, 7, ...
- ℓ is the Azimuthal or angular momentum quantum number. It can have integer values from 0 to n -1: 0, 1, 2, 3, 4, ...
- mℓ is the magnetic quantum number, which can have values from -ℓ to + ℓ
- ms is the spin quantum number. which can have values +1/2 and -1/2.
In this way, Pauli's exclusion principle implies that two electrons occupying the same orbital will have equal n, ℓ, and mℓ values, meaning that their ms will be opposite: + 1/2 and −1/2.
