The molecular orbitals of conjugated pi bonds Ethene Butadiene Hexatriene 元*2 3 兀 π*2 LUMO 元*，UMo 1 元*1LUM0 △E △E △E 2 HOMO 元3HOMO 元HOMO x2 1 1 Note that the energy gap AE(HOMO-LUMO gap)decreases (becomes smaller)as the number of conjugated pi orbitals increasesThe molecular orbitals of conjugated pi bonds