What characterizes aromatic compounds in organic chemistry?

Aromatic compounds are characterized by their unique electronic structure that allows for resonance delocalization of electrons. This delocalization occurs in a cyclic, planar arrangement of atoms, typically containing conjugated pi bonds. The resulting stabilization from electron delocalization contributes to the distinct properties of aromatic compounds, such as their heightened stability compared to non-aromatic compounds.

This resonance structure can be depicted by drawing multiple contributing structures, which indicates that the electrons are not localized between two atoms but spread across the entire aromatic system. This feature is a key defining characteristic of aromaticity and is crucial for understanding the reactivity and properties of these compounds in organic chemistry.

The other characteristics mentioned in the options do not apply to aromatic compounds in defining ways. For instance, aromatic compounds can contain both single and double bonds, are not consistently non-polar (as many can be polar based on their substituents), and their solubility in water varies widely rather than being universally soluble.