Formal Charges

Formula: Formal charge = valence electrons − lone pair electrons − ½(bonding electrons).
Atoms with more bonds than usual get a positive formal charge; fewer bonds means negative.

Quick Patterns

Nitrogen with 4 bonds → +1. With 2 bonds and a lone pair → −1.
Oxygen with 3 bonds → +1. With 1 bond and 3 lone pairs → −1.
Carbon with 3 bonds and a lone pair → −1. With 3 bonds and no lone pair (empty p) → +1.

Resonance & Formal Charges

Moving electrons between resonance forms changes where formal charges appear.
The total charge of the molecule stays the same across all resonance forms.
Formal charges help you track electron flow when drawing resonance arrows.

Identify Partial Charges

Partial charges (δ+ and δ−) mark where the resonance hybrid carries real charge character: an atom bearing a formal charge in a significant contributor keeps a fraction of that charge in the hybrid.

Tap every atom with the requested partial-charge character in each molecule below.

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