Requirements for aromaticity

•	We can now summarizes what we have discovered: A molecule can only be aromatic if it has a planar (so that p-orbitals can overlap) system of conjugation with 4n+2 π electrons (where n = 0, 1, 2, 3...) i.e. only molecules with 2, 6, 10, 14, 18... π electrons can be aromatic.

•	This is the basis for Huckels Rule, which states “Planar, fully conjugated, monocyclic systems with 4n+2 π electrons (n = 0, 1, 2, 3...) have a closed shell of electrons all in bonding orbitals and are exceptionally stable. Such systems are said to be aromatic”