A LITTLE LIGHTBULB MOMENT
Acid-base chemistry, resonance and electron flow
Resonance means electron delocalization, not atom movement
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Push electrons, never atoms, in resonance drawings.
The idea behind the cue
Resonance structures are alternative valid electron arrangements for the same atom connectivity. In curved-arrow resonance, only electrons move, not nuclei. The real molecule is a resonance hybrid with delocalized electron density.
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Short & simple
Push electrons, never atoms, in resonance drawings.
Acronym
BN — Bouncy Noodles.
Story
A cartoon chef slides sauce between pizza slices without moving the slices. The toppings stay put, but the flavor spreads. That is resonance: the electron sauce moves; the atoms do not.
Connect the pieces
- B (Bouncy) → Bond electrons: Only electrons shift in resonance; the atom framework stays the same.
- N (Noodles) → Nuclei fixed: Nuclei and atom connectivity do not move in resonance drawings.
- Bouncy · Bond electrons: Only electrons shift in resonance; the atom framework stays the same.
- Noodles · Nuclei fixed: Nuclei and atom connectivity do not move in resonance drawings.
Know the limits
This applies to resonance depictions; real molecules can still rotate bonds or undergo other non-resonance motions.
Further reading · OpenStax Organic Chemistry ↗Check your understanding
Which statement best describes resonance structures?
A. They represent distinct molecules isolated in equilibrium.
B. They differ only in electron placement, not atom connectivity.
C. They are rapidly interconverting constitutional isomers.
D. They show different possible atom skeletons for the same molecule.
Reveal explanation
They differ only in electron placement, not atom connectivity.
Resonance structures keep the same atom connectivity and differ only in electron placement.