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Rule that Guarantees all Re-Arranged Lewis Structures?

Posted: Tue Jan 31, 2017 4:17 pm
by Michael_Johanis_2K
For HW 9.25, to calculate the residual entropy of SO2F2, we need to draw out all the arrangements of the Lewis structure. I found that there are 6 different arrangements. After find the degeneracy, I used to S = Kb lnW.

Is there a method to be sure that I have drawn out every possible Lewis structure? After drawing out all 6 re-arrangements of the Lewis structure, I spent a little time wondering if there were more Lewis structures that I missed.

Is there a rule that relates molecular geometry and # of unique atoms to the total possible arrangements? When doing problems like these, does anyone have advice on how to know that you have drawn out all combinations?

Re: Rule that Guarantees all Re-Arranged Lewis Structures?

Posted: Tue Jan 31, 2017 8:44 pm
by Chem_Mod
Hello Michael,

I cannot think of a method that is one hundred percent full proof of ensuring that you find every Lewis structure. I think unfortunately most of the time you will have to hope that you have gotten all the possible combinations.

But I what I have found to be useful is that you can generally guess how many possible configurations based on the number of surrounding elements. Generally if they are each different and unique you would expect to have far more than if one or two of them were similar.