Polar

[Matia Kim 1B]

How do you know which resonance structure to use if they are polar? Is it always by lowest charge?

[Michael_Navarro_1H]

Usually, you want to keep the negative charges on the most electronegative atoms and keep the other atoms at a FC of 0.

[Daniel Lai]

If the formal charges are close to 0, then you use that one.

[Daniel Lai]

Polarity does not affect it, only having the formal charges closest to 0 matters.

[204765696]

You use the one with formal charges closest to 0.

[melodyzaki2E]

polarity shouldn't affect the resonance structure, focus on the formal charge when determining resonance.

[kimberlyrose1G]

You calculate the formal charge of each possibility and focus on the one that has an f.c. closest to zero

[MichaelMoreno2G]

Can someone explain how we identify if a bond is polar or non-polar?

[LuisG14A1J]

Can someone explain how we identify if a bond is polar or non-polar?

To identify if a bond is polar or non polar depends on the structure of the molecule. If the Dipoles all cancel each other out when all the directions are considered for the structure then the molecule is non-polar. Polarity usually occurs as a result of Electron Lone Pairs offsetting all the molecules from each other.
Bonds can be polar if the Formal Charge (FC) of the two elements being considered are different in their FC.
But for most structures that express non-polar characteristics like HF: It's linear structure, FC cancels out on both H and F to be 0. The way to determine if that molecule is polar or non polar is by the unequal sharing of electrons. Fluorine unequally shares the electrons with Hydrogen, resulting in a slight negative charge on the shape of it. (If you look up how an HF molecule looks it looks tear drop shaped because of the large electron shell of the Fluorine atom holding the electrons) F holds all the electrons and creates a small net negative charge in that direction, and H has so few electrons near it that it creates a small net positive charge in its direction. It's because of the high electro-negativity of the Fluorine atom.