Dipole Moments Polar Covalent Bonds: Dipole Moments

ResonanceResonance forms• Individual line-bondstructures of a molecule orion that differ only in theplacement of andnonbonding valenceelectrons• Indicated by “ ”• Resonance formscontribute to a single,unchanging structurethat is the resonancehybrid of the individualforms and exhibits thecharacteristics of allcontributorsResonanceBenzene has two equivalent resonance forms• The true structure of benzene is a hybrid of the twoindividual forms, and all six carbon-carbon bonds areequivalent• Symmetrical distribution of electrons is evident in anelectrostatic potential map of benzene2.5 Rules for Resonance FormsRule 1 – Individual resonance forms are imaginary, notreal• Real structure is a compositeRule 2 – Resonance forms differ only in the placement oftheir or nonbonding electrons