CHM136H1 Lecture Notes - Lecture 6: Lewis Structure, Pi Bond, Benzene

• School: UTSG
• Department: Chemistry
• Course: CHM136H1

Document Summary

To help describe the bonding structure for delocalized pi-bonds. This model uses localized diagrams to represent delocalized. E- finds themselves in fields of more than one field of nucleus. Sharing of e- among many atoms stabilizes molecules. Deloc bonding desc by combo of resonance forms is more stable than bonding by and indiv resonance forms alone. Benzene is also a resonance structure - the 6 c-c bonds are all identical in length. Visualize p-orbitals alongside the lewis structure to observe the resonance. There is no oscillation of single/double bonds within the ring - it"s both at the same time. So there"s a full sigma and a partial pi bond on all bonds at the same time. Below is the convention of drawing the delocalized benzene structure. Only the arrangement of the e- changes - nuclei doesn"t move. Resonance forms differ in placement of pi-electrons and non-binding e- Each form must be valid lewis structure and obey valence rules.