MO's of Benzene Benzene's extra stability cannot be explained by resonance alone,and so we must turn to Molecular Orbital theory for a fuller answer. Benzene has 6 planar sp'carbons,and therefore each carbon has an unhybridized p orbital. These p orbitals are perfectly aligned for overlap(ie.bonding,just like for a bond) These p orbitals create a continuous ring of orbitals above and below the plane of the carbon atoms. The 6 overlapping p orbitals create a cyclic system of molecular orbitals(i.e.a three dimensional system). Even though we have only seen two dimensional MO's previously(ethene,allyl systems,the same basic rules apply. 1)Six p orbitals are used in the benzene system,therefore six MO's are created. 2)The lowest energy MO is entirely bonding(constructive overlap between all adjacent p orbitals,no nodes). 3)The number of nodes increases as the MO's increase in energy. 4)The MO's must be divided between bonding and antibonding,with the possibility on non-bonding MO's in some cases. The 6 MO's for benzene can be drawn either in 2D or 3D projections. Ch16 Aromatic Compounds (landscape).docx page 8Ch16 Aromatic Compounds (landscape).docx page 8 MO's of Benzene Benzene's extra stability cannot be explained by resonance alone, and so we must turn to Molecular Orbital theory for a fuller answer. Benzene has 6 planar sp2 carbons, and therefore each carbon has an unhybridized p orbital. These p orbitals are perfectly aligned for overlap (i.e. bonding, just like for a  bond). These p orbitals create a continuous ring of orbitals above and below the plane of the carbon atoms. The 6 overlapping p orbitals create a cyclic system of molecular orbitals (i.e. a three dimensional system). Even though we have only seen two dimensional MO's previously (ethene, allyl systems, the same basic rules apply. 1) Six p orbitals are used in the benzene  system, therefore six MO's are created. 2) The lowest energy MO is entirely bonding (constructive overlap between all adjacent p orbitals; no nodes). 3) The number of nodes increases as the MO's increase in energy. 4) The MO's must be divided between bonding and antibonding, with the possibility on non-bonding MO's in some cases. The 6 MO's for benzene can be drawn either in 2D or 3D projections