# quantum numbers

#### ds2012tg

##### Full Member
Can anybody help me with this? Why is the answer A? I don't get how the azimuthal number is 0. I thought it would be 1 because the valence electrons are in a p orbital.

6) Which of the following is a possible set of quantum numbers [n,l,ml,ms] for a valence electron in bromine?
A) [4,0,0,-1/2]
B) [3,1,1,+1/2]
C) [4,1,-2,+1/2]
D) [3,2,-1,-1/2]

thanks!!!

#### Msmouth

##### Full Member
7+ Year Member
Can anybody help me with this? Why is the answer A? I don't get how the azimuthal number is 0. I thought it would be 1 because the valence electrons are in a p orbital.

6) Which of the following is a possible set of quantum numbers [n,l,ml,ms] for a valence electron in bromine?
A) [4,0,0,-1/2]
B) [3,1,1,+1/2]
C) [4,1,-2,+1/2]
D) [3,2,-1,-1/2]

thanks!!!

Bromine is level 4 for s or p shell. So you have a choice between between A & C. For C if l=1 than you can only have values for ml = from -1 to 1.
A works because if you have l=0, then ml only can = 0.

Hope this helps!

#### FeralisExtremum

##### Full Member
10+ Year Member
Bromine is level 4 for s or p shell. So you have a choice between between A & C. For C if l=1 than you can only have values for ml = from -1 to 1.
A works because if you have l=0, then ml only can = 0.

Hope this helps!

I'd like to expand on Msmouth's answer a bit. This does explain why C cannot be the answer via process of elimination, but I understand his confusion as well: looking at Bromine's position on the periodic table, it appears to him that it should lie within the p subshell, for which l = 1. He wants to know why it is possible for Bromine's valence electrons quantum number to have a value outside of that, in this case l = 0 which is the s subshell.

Bromine itself isn't actually within the p subshell - rather, it has valence electrons available up to and in the p subshell. But remember that this question is asking potential quantum number for Bromine's valence electrons. That refers to all 7 of the electrons in Bromine's outer shell which includes the ones that are in the s subshell, hence why l=0 is valid in the answer.

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#### ds2012tg

##### Full Member
ohhhhhh that makes much more sense!!!!! awesome thanks!

#### spoog74

##### Full Member
5+ Year Member
ohhhhhh that makes much more sense!!!!! awesome thanks!

yes ^ he is right. The electron configuration for Bromine is 4S2 3d10 4P5. 4S2 and 4P5 are valence

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