Writing Resonance Structures
Professor Gary R. Gray
1. Resonance structures only involve a change in electron organization.
H C H C C H H H H C C C H
H These are different compounds and are not resonance structures.
Identical electronic arrangements are of equal importance.
O H C O H O C O
equal contributors, C-O bond order 1.5 O O C O O O C O O O C O
equal contributors C-O bond order 1.33
Structures containing the greater number of covalent bonds are more important. This is equivalent to saying that structures in which atoms have filled octets are more important.
H C O H H H major contributor H C N H H H C O H
H C N
H H major contributor
H C O H C O
major contributor F F C F F C F major contributor F
Structures involving a minimum of charge separation are more important.
H C H O H O H C O H H C O
major contributor O H C O H
Structures in which negative charges are borne by more electronegative elements and positive charges are borne by more electropositive elements are more important.
O H C C H H C N N H H major contributor H H O C C H
H major contributor H C N N
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