How is NH3 acting in the reaction H++:NH3[H:NH3]+according to the Lewis definition?

1 Answer
Jan 4, 2015

NH3 is acting as an electron donor, so by definition it is a Lewis base.

The lone pair of elctrons from the N-atom is (mainly) donated to, are shared with, the proton (H+), after which all four H's fill up a nice tetrahedron around the N.

The representation of [H:NH3]+ is not really correct, as all H-atoms are completely equal, and the electron deficit (the overall +) is shared around the whole [NH4]+ ammonium -ion.

If the ammonium-ion is dissociated (e.g. in hot alkalic surroundings), there is no telling which of the four H's will leave.