Practice!

Sample Problem

n

l

ml

ms

2

1

0

X

 

n

l

ml

ms

2

1

0

Y

 

If the above quantum numbers describe two different electrons in a fluorine atom, and the magnetic spin number X is +1/2, what is the magnetic spin number of Y?

Solution

The Pauli Exclusion Principle states that no two electrons can have the same four quantum numbers. Therefore, if X = +1/2, then the second electron must spin in the opposite direction (Y = -1/2).