*Resonance can be considered as the condition occurring when more than one valid Lewis structure can be written for a particular molecule. This can happen any time there are two or more adjacent p-type orbitals in the same plane.
*Rule 1: Resonance structures must have the same number of electrons.
*Rule 2: All resonance structures must be valid Lewis dot structures.
*Rule 3: The hybridization does not change between resonance structures.
*Rule 4: The positions of atoms are the same in all structures.
*Rule 5: Resonance structures do not have to be equivalent.