Organic Chemistry – Some Basic Principles Part 1

(b) For aromatic compounds following conditions should be satisfied
(i) planarity
(ii) complete delocalisation of π-electrons in the ring.
(iii) presence of (4n+2)π-electrons in the ring, where n=0,1,2,... .
This is called Huckel rule.
‌ e.g. ‌n‌‌=0,2πe−
n‌‌=1,6πe−
n‌‌=2,10πe−