Chemistry · Chapter 7

Resonance and Formal Charge

Some species need more than one drawing. Flip through the forms, score every atom with formal charge, and see which structure the rules prefer.

The structure O₃

A resonance form with formal charges

Badges show formal charge. Dots are lone pairs.

How the forms score lower is better

Choose a species

Formal charge, atom by atom

    Charges add to
    0
    Charge load
    2

    Formal charge = valence − lone pair electrons − half the bonding electrons.

    What you are seeing
    Ozone, two equal forms
    Both forms score the same, so neither one is the molecule.