Question

Is the lone-pair of electrons on the ammonia molecule delocalized?

Answer 1

Not to my knowledge.........

Explanation:

We gots `H_3N:`....the lone pair is localized on the nitrogen atom, and this is the nucleophilic centre.

On the other hand, the nitro group, `NO_2^-` or `""^(-)C-=N:` could potentially bind thru either atom in the molecule. As always, the organic chemist exploits reaction conditions that select a particular reactivity.

Answer 2

No it's not.

Explanation:

Ambident nucleophiles have negative charge delocalised over two unlike atoms (or over two like, but not equivalent atoms). Things like enolates would be ambident nucleophiles, but in ammonia `NH_3` there is no such delocalisation.