The tropylium ion is a 7-membered carbon ring. What must its formal charge be to ensure it is fully — Hydrocarbons Chemistry Question

💡 Solution & Explanation

The cycloheptatrienyl (tropylium) cation has three double bonds ($6\pi$ electrons). The 7th carbon must hold a positive charge (an empty p-orbital) to complete the cyclic conjugation loop without adding more electrons ($4n+2=6$).