Selecting the dominant resonance structure.

[Miguel Hernandez LEC 3]

From my understanding, the most important factors to look at when determining the most dominant resonance structure is ensuring that the octet rule is fulfilled and ensuring that the formal charge is as low as possible. If the octet rule is met and different structures have the same formal charges, what are some additional factors you must look at to determine the dominant structure?

[205538966]

A resonance structure is more stable if a negative charge resides on a more electronegative atom. For two resonance forms with the same formal charges, the resonance structure that has the negative formal charge on the more electronegative atom will be more stable.

[Ryan Lim 2I]

Another factor you can look at is that the dominant resonance structure will have the least nonzero formal charges, and also to check that the least electronegative atom is in the center of the molecule.