Question

Which one of the following represents an acceptable set of quantum numbers for an electron in an atom? (arranged as n, l, ml, and ms)

2, 2, -1, -1/2


3, 3, 3, 1/2


3, 3, 3, -1/2


5, 4,- 5, 1/2


2, 1, 0, 1/2

Answer 1

First, since l = n-1,
5,4,-5,1/2 and 2,1,0,1/2 are the only answer choices left.
Next, since ml = -l to l,
2,1,0,1/2
is the answer because in 5,4,-5,1/2, the ml value of -5 is not in the range of -4 to 4, as notes by the value 4 for l.