Hückel's rule
= Hückel's rule
{c}
{title2=$4n+2$}
A monocyclic, approximately planar, continuously conjugated pi system with $4n+2$ pi <electrons> has a closed-shell aromatic configuration in the elementary Hückel model, where $n$ is a <nonnegative integer>. Fused systems and <heterocycles> require a specified orbital and <resonance (chemistry)> description rather than counting every drawn <double bond> in each polygon.