Is ammonia a polar or nonpolar molecule?

Answer 1

Polar.

Nitrogen in ammonia has 3 bonding pairs of electrons and one non-bonding pair of electrons around it. The repulsion of the pairs of electrons for other pairs of electrons result in a tetrahedral arrangement of the electron pairs around the N.

But only 3 of the pairs are bonding. This results in a shape like a pyramid, with the non-bonding pair at the top... So this molecule has a partially negative end (the non-bonding pair), and a partially positive "end" -- the 3 H atoms at the base of the pyramid, actually, a plane through the 3 N-H bonds, with the H 's on one side and the N and its non-bonding electron pair on the other side, since it is the 3 N-H bonds which are polar.

So NH3 is polar due to polar bonds, and a nonsymmetrical shape..

Answer 2

Ammonia is polar, but not as polar as is water in aqueous solution. It has a structure with nitrogen at the center of a tetragonal pyramid. On 3 corners are hydrogen that N bonds to. On the other corner are two unshared electrons, which "squash" the tetragon slightly.