Is the ammonium substituent (-NH3+) really meta-directing in electrophilic substitution?

Question

If we make a resonance structure for the anilinium ion, with positive charge at either the *ortho* or the *para* position, we get a pentavalent nitrogen, which is not possible. So, how is the $\\ce{-NH3+}$ group *meta*-directing in electrophilic aromatic substitution reactions, e.g. in nitration of aniline under acidic conditions?

Answer 1

It's an inductive effect, not a resonance effect. Draw all the resonance structures for the carbocation intermediate. None of them involve the nitrogen directly. Positive nitrogen is very inductively withdrawing.