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HW #3.49 (6th Ed)

Posted: Wed Nov 14, 2018 10:49 am
by Imelda Mena 3I
Hi all!

For this HW problem, why do we have the oxygen in parts a and c have a positive charge of 1 if it is more electronegative than N and C?

Re: HW #3.49 (6th Ed)

Posted: Wed Nov 14, 2018 11:54 am
by Heesu_Kim_1F
The +1 charge on the Oxygen is referring to the formal charge. For part (a), the total number of electrons is 5 (N) + 6 (O) - 1 (overall +1 charge) = 10 electrons. For part (c), the total number of electrons is C (4) +6 (O) = 10 electrons. For both parts, the only way to fulfill 10 electrons without going over is to place a triple bond between the two elements. When we do that, the formal charge on N and C is 0 and O is +1. I think in cases where there can be different structures that work, you would utilize electronegativity as a tool to find the most stable structure; otherwise, you would not. Hope this helps!