CHM 11500 Lecture Notes - Lecture 16: Octet Rule, Formal Charge

• School: Purdue University
• Department: Chemistry
• Course: CHM 11500
• Professor: Chittaranjan Das

Document Summary

Chm 115 - lecture 16 - resonance, octet rule exceptions, and formal charge. For some molecules, there are multiple correct lewis structures that can be written to represent them. Experimental evidence shows that these molecules are actually a hybrid of the different lewis structures. For ozone as shown above, evidence shows that both o-o bonds are the same length, indicating that each bond is a hybrid of a single bond and a double bond. These types of molecules are referred to as resonance hybrids. In some cases, some resonance structures contribute more to the overall structure of the molecule than others. This depends on the relative stability of the structures. Certain molecules can be formed that don"t subscribe to the octet rule. Odd-electron elements can sometimes form these molecules. Heavier noble gases can form molecules through expanded octets. Formal charge is the charge assigned to a specific atom in a molecule under the assumption that all bonds share electrons equally.