Molecular and Ionic Compound Structure and Properties

2.6 Resonance and Formal Charge

Essential Knowledge:

*These are taken directly from College Board

• In cases where more than one equivalent Lewis structure can be constructed, resonance must be included as a refinement to the Lewis structure. In many such cases, this refinement is needed to provide qualitatively accurate predictions of molecular structure and properties.  (SPQ-1.A.1)  

• The octet rule and formal charge can be used as criteria for determining which of several possible valid Lewis diagrams provides the best model for predicting molecular structure and properties.  (SAP-4.B.2) 

• As with any model, there are limitations to the use of the Lewis structure model, particularly in cases with an odd number of valence electrons (SAP-4.B.3 )