Pauli Exclusion and Spin

Most recent answer: 05/16/2018

Q:
Two electrons can occupy the same atomic orbital if their spin quantum numbers are opposite. Does this have anything to do with the magnetic fields they generate being opposite?
- Sara Fishman (age 72)
Worcester, MA, USA
A:

The magnetic fields from the spin are opposite, but even if the electrons were uncharged and made no magnetic fields, the same rule would apply. The point is that the quantum states of two fermion particles cannot be the same. If the orbitals are the same, then something else must be different, and the spin is the only other property those electrons have that can be different.

Mike W.


(published on 05/16/2018)

Follow-Up #1: spin and charge

Q:
OK, I found an answer to my other question on your site, although my search originally turned up empty. The answer connected the Pauli Exclusion Principle to magnetic fields due to spin cancelling out. (And obviously I'm not a child, tho you might say I'm in my "second childhood.") But the answer to my first question generates another question: Does the cancelling out of magnetic fields also cancel out the electrical repulsion due to the electrons having the same charge? I promise I'll go sit with the grownups after this.
- Sara Fishman (age 72)
Worcester, MA, USA
A:

Hey, us old folks should stick together. This site is for all ages.

The magnetic cancellation doesn't make the electrical fields cancel. Since the charges are the same (unlike the spins, which are opposite) the electrical fields add up.

Mike W.


(published on 05/16/2018)

Follow-up on this answer