Topic overview

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Aromaticity depends on a cyclic, planar, conjugated π system containing (4n + 2) π electrons. Comparing this pattern with anti-aromatic and non-aromatic systems helps distinguish their structural requirements. Benzene provides a central example: its π electrons are delocalized, and its carbon–carbon bonds are equal in length. Naming builds on this structure through benzene numbering, lowest locants, alphabetical ordering, and familiar parent names such as toluene and phenol. The topic also introduces ortho, meta, and para relationships, fused benzenoid systems, annulenes, aromatic ions, and heteroaromatics, including how heteroatoms affect electron contribution and numbering. Together, these ideas support a systematic approach to identifying aromatic structures and interpreting their names.