how can you find the angular momentum quantum number (l) for the orbital from which a Mg atom loses two electrons to form a Mg2+ ion?
Okay, Mg in ground state has an electron configuration of [Ne]3s2.
It loses two electrons from the outermost energy level, 3s subshell, when Mg 2+ forms.
For 3s,
n= 3
l = 0 (for s subshell)
ml = -l to +l for any electron, so it would be 0 in this case
In general remember that, for an electron in
- the s subshell, l = 0
- the p subshell, l = 1
- the d subshell, l = 2
- the f subshell, l = 3
Don't you find "l" by using n-1? since the electrons are being lost from shell 3 (n=3), then should "l" be 2 (3-1) .
Don't you find "l" by using n-1? since the electrons are being lost from shell 3 (n=3), then should "l" be 2 (3-1) .
No.
n-1 tells you how many levels of subshells(aka orbitals) are possible for a particular energy level. For a particular energy level, the possible l values are 0 to n-1.
Look at the first energy level, n=1. So the possible subshells for n=1, are 1-1 =0. 0 denotes the s subshell. And that makes sense because the first energy level only has the s subshell.
For the second energy level, n=2. So the possible subshells here are 0 to 1 (n-1).
So the second subshell can have the s subshell (denoted by l=0) and the p subshell (denoted by l=1). Again that makes sense because we only have 2s and 2p subshells and NOT 2d.
For n=3, the possibilities are 0 to 2 (n-1). So we can have l=0 for s subshell, l=1 for the p subshell, l=2 for the 3 subshell. And we know we only have 3s, 3p, and 3d subshells.
Does that help?
I'd just like to mention something that you may not have realized.
The quantum stuff you're asking about here will at most be 1 question on the mcat if it shows up at all. Unless you're nearing the end of your studying and are solid on everything else, I'd devote my time to higher priority material to maximize your score. This is one more reason why taking a lot of practice tests is such an important part of mcat studying. Its important to figure out what material is priority material and what isn't.
-cj8
Let me see if I go this right..
There are shells (principal quantum number n)
There are subshells or orbitals (l angular quantum number which is 0 to n-1).
Since Mg is losing electrons from the third shell (n=3) then l can be 0,1 or 2. And since the 2 electrons are being lost from the s orbital l has to be 0. if the electons were being lost from the p orbital then l would be 1 and if they were being lost from the d then l would be 2. is this right?
To find m(l) you would go l-1to l+1...so m(l) would be-1to1? Can m(l) be negative?
To find m(s) it would either be up +1/2 or down-1/2. Does the orbital fill with the +1/2 first before the -1/2?
Thanks for your help.