Return to Contents Chapter 4: Resonance Ch 1 contents

Recognising Resonance Structures

Being able to quickly recognise valid resonance structures is a very valuable skill.

The most common errors involve thinking that a structures are resonance structures when they are not rather than not recognsing ones that are.

Another common error is either using the wrong arrow to indictate resonance or misusing the resonance arrows by confusing the resonance symbol and the equilibrium symbol which have quite different implications. They are not interchangeable !

resonance arrow
  
equilibrium arrow
resonance
  
equilibrium

 

Rules to remember for recognising resonance structures:
  • Atoms never move.
  • You can only move electrons in π bonds or lone pairs (that are in p orbitals)
  • The overall charge of the molecule must remain the same.
  • The bonding framework (sigma framework) of a molecule must remain intact.

Are these resonance structures ?
   
resonance structures ?
 ANSWER  
resonance ?
 ANSWER  
resonance ?
 ANSWER  
   

Problems

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© Dr. Ian Hunt, Department of Chemistry University of Calgary