[ahhppull]

I need some help with term symbols. I'm not entirely sure on how to do these.

What are the possible term symbols for the following electron configurations?
1) 1s2 2s2
2) 1s2 2s1 3s1
3) 1s2 2s2 2p2

For #1, I got ²P_1/2
For #2, I'm not sure how to do this.  It is in an excited state?
For #3, I got ²P_1/2 and ²P_3/2

[Corribus]

Term symbols: the bane of every p-chem student's existence.  I remember leading TA sessions on the topic and by the time we were done - hours later - both the students and myself needed some serious quantities of beer. 

I'd say the first thing to do is realize that a given electron configuration typically has more than one term symbol associated with it, because there are multiple electronic states that can have the same general electron configuration.

That realized, you need to write out every possible microstate for that electron configuration, THEN figure out the term symbol associated with that group of (identical) microstates.  There is actually a pretty nice step-by-step guide available at wikipedia.

http://en.wikipedia.org/wiki/Term_symbol

Check it out, see if you can't figure your problems out, then come back with additional questions. 

[ahhppull]

Thanks for the link!

So after reading the wiki, I found out that #1 should be ¹S₀.  For #3, it was the same example used, and I almost fully understand it.

What about #2?  Is it the same procedure as #3?

[ahhppull]

I also have another homework problem.  It asks for the possible term symbols for ground state of chlorine.

So by following the procedure in wiki, there should be 6 microstates.

          ML = 1 MS =1/2
     ML = 1 MS =-1/2
         ML = -1 MS =1/2
    ML = -1 MS =-1/2
         ML = 0 MS =1/2
     ML = 0 MS =-1/2

I haven't finished the problem, but am I on the right track?

[Corribus]

Looks like you're on the right track.
Also, for closed shell atoms in their ground state, the term symbol is always ¹S₀.  Easy shortcut to remember.

[ahhppull]

Looks like you're on the right track.
Also, for closed shell atoms in their ground state, the term symbol is always ¹S₀.  Easy shortcut to remember.

Thanks, I figured it out, but I still am unsure of what to do for #2 where the electrons are in an excited state.  Since its not in the ground state, its not ¹S₀Do I follow the same procedure as the previous problems?

[Corribus]

Yes, you follow the same procedures.  Just write out what all of the possible microstates are (all the orbital combinations) and you can't really get into trouble.  I always found it help to tabulate it all in the manner shown in the wikipedia article.  It was pretty hard to screw it up when you do it that way.