Is NH3 Polar or Nonpolar?

Answer: NH3 (ammonia) is a polar molecule because partial charges are not dispersed equally around the molecule with a region of negative charge near the top (i.e. the lone pair electrons) and a region of relative positive charge by the hydrogen atoms. 

There is certainly a large electronegativity difference between N (3.04) and H (2.20) causing these polar covalent bonds. This in turn results in an unequal dispersion of electrons and therefore electric charge within the molecule. Since the structure is "bent" as a result of lone pair electron-electron repulsion, these polar covalent bonds cause a strong partial charge. In fact, the partial charge is much stronger than typical dipole interactions and is one of only three bond types that are permitted the capability of "hydrogen bonding." The other two types of bonds include -OH and -FH molecules (either those with these groups attached or in their natural forms: NH3, H2O and FH).

However, between the different hydrogen bond types NH3 is the weakest, H2O is relatively strong and FH is the strongest dipole interaction because of the increasing differences in electronegativity. As a result, NH3 is a colorless gas at room temperature as opposed to H2O which is a liquid (water) at room temperature.

To learn more about why NH3 is polar, read more about the lewis structure for NH3.

NH3 Molecule Ball and Stick
NH3 Molecule Ball and Stick Diagram. Created with Avagadro.
What are the most common uses of ammonia (NH3)?

The two most common uses are as fertilizer and in cleaning products. The former accounts for nearly 88% of ammonia usage in the United States [1]. Ammonia acts in a similar fashion to water in both cases; however, it has the effect of increasing output for certain agricultural crops.