BONDING + STRUCTURE

• WHAT IS AN ARENE?

  hydrocarbon based on benzene (C6H6)

  -> previously known as aromatic compounds
• WHAT IS A BENZENE?

  unsaturated but very stable hexagonal molecule with a special type of bonding
• WHY DID BENZENE'S STRUCTURE CONFUSE SCIENTISTS FOR SO LONG?

  • unsaturated but does not readily undergo addition reactions
  • all carbon atoms were equivalent, so all C-C are the same
• GENERAL DESCRIPTION OF BENZENE?

  • planar molecule
  • flat, regular hexagon of carbon atoms each bonded to a single hydrogen atom
  • C-C bond lengths are intermediate between C-C and C=C due to some delocalised electrons
  • form a region of electron density above and below ring
  • meaning benzene is unusually stable ("aromatic stability")