<Li> the molecule must have 4n + 2 electrons in a conjugated system of p orbitals (usually on sp - hybridized atoms, but sometimes sp - hybridized); </Li> <Li> the molecule must be (close to) planar (p orbitals must be roughly parallel and able to interact, implicit in the requirement for conjugation); </Li> <Li> the molecule must be cyclic (as opposed to linear); </Li> <Li> the molecule must have a continuous ring of p atomic orbitals (there cannot be any sp atoms in the ring). </Li>

Using huckel's aromatic rule prove naphthalene is a aromatic compound