How do we draw the Lewis structure of ammonia?

So ammonia, $N {H}_{3}$, has 8 valence electrons to distribute. 6 electrons are utilized for the 3 $N - H$ bonds, and the remaining 2 are localized on the nitrogen as a lone pair.
So we get $: N {H}_{3}$. Note that this is not the end of the story. Why have I represented each atom in the molecule as neutral? If I had ammonium ion, ${\left(N {H}_{4}\right)}^{+}$, the positive charge is associated with the nitrogen centre. For the nitrogen in ammonia, there are 7 positive nuclear charges (i.e. 7 nuclear protons). This charge is balanced by 2 inner core electrons, 2 electrons from the lone pair, and 3 electrons from the $N - H$ bonds (i.e. the other electron in the $N - H$ bond is formally assigned to the hydrogen).