The main difference between polar molecules and nonpolar molecules lies in the arrangement of atoms in the molecule. Additionally, polar molecules have an electrical field charge, while nonpolar molecules do not possess an electrical field charge, explains School-For-Champions.com.
In polar molecules, there is a uneven distribution of electrons around the molecule. When one side of the molecule has more atoms, or electrons, than the other side, a positive electrical charge and a negative electrical charge form. In nonpolar molecules, there is an even distribution of electrons around the molecule, so the charges cancel each other. Water is a common example of a polar molecule.
A water molecule is arranged so there are excess electrons around the oxygen molecules and a lack, or deficiency, of charges around the hydrogen molecule. Ammonia, hydrogen sulfide and sulfur dioxide are a few more examples of polar molecules. Carbon dioxide is a common example of a nonpolar molecule. A molecule of carbon dioxide does not have a charge because the electrons are evenly distributed around the carbon molecule and the oxygen molecules. Gasoline and toluene are a couple of examples of nonpolar liquid molecules. Helium and neon are examples of nonpolar gas molecules.