Benzene, Trends and Patterns

The bonding and structure of benzene was a puzzle for a long time because:

• Benzene was more stable than expected.
• Reacted to substitution than addition.
• All the carbon atoms were equivalent, which implied that all the carbon-carbon bonds are the same.

Structure and Bonding of Benzene

• The carbon atoms are bonded by alpha-bond.
• Molecular ordital shaped like a doughnut, above and below the ring, extending over all six carbon atoms.
• This has been made by the overlap of p-orbital-one from each carbon atom.
• The electrons in this orbital are delocalised and form a pie-orbital.
• Delocalisation means electrons are spread over more than two atoms-in this case the six carbon atoms that form the ring.
• Each carbon atom has 3 electrons making it an intermediate between a single and a double bond.