Resonance

[Cecilia Cisneros 1F]

Can someone explain how the other two lewis structures are apart of the resonance structures? I thought resonance would have to be only with the lowest energy structure. In this case isn't the last one the only one that would be the lowest energy structure with all formal charges = 0. Therefore this compound would not have resonance?

[Claire_Latendresse_1E]

In the picture, the last resonance structure would be the best because all of the formal charges are zero like you said. That doesn't mean that it is the actual structure, though. Every resonance structure contributes to the overall "actual" molecule. The last resonance structure will contribute more than the other two structures because of its stability due to formal charges.

[magalysantos_1F]

Resonance does not necessarily mean the lowest energy structure. Resonance is all possible Lewis structures of a molecule, in which you can find the most stable structure (because it will have the lowest energy).

[OwenSumter_2F]

To add on to what the others have said, if you are asked to give the most probable Lewis structure, you would give the last one with the lowest formal charge, however resonance is all possible structures.

[Rachel Jiang 3H]

All resonance structures contribute to the overall structure of the molecule regardless of their formal charges. However, the resonance structure with the least amount of formal charges is the most stable structure, and should contribute the most to the overall structure. Hope this helps!