Aromaticity and It's Differences to Resonance

[Chem_Mod]

Question: What is the difference between aromaticity and resonance?

[Chem_Mod]

Answer: Having resonance does not mean it is aromatic. To be aromatic, it must be a ring carbohydrate with conjugated pi bonds (and there must also be 4n+2 number of C in the same plane in the ring. These conjugated pi bonds have resonance.

[Chem_Mod]

Q: What does it mean when a molecule is aromatic? Is it when there's a consistent switch between double and single bonds in a cyclic molecule or can it be inconsistent (i.e. double bond, single, single, double, etc).

[Chem_Mod]

A: A "consistent switch between double and single bonds in a cyclic molecule" is correct. But remember you are thinking of the molecule as a Lewis structure. The real structure (e.g., benzene) will have identical bonds that are shorter than single bond but longer than a double bond (i.e., partial double bond character).