A polar molecule is when the arrangement of the atoms in molecules are unequal where one end of the molecule has a positive charge while the other end has a negative charge. Examples of a polar molecule are water, ammonia, hydrogen sulfide and sulfur dioxide. The opposite is called a nonpolar molecule. These molecules would share their electrons equally resulting to having no partial charges in the molecule. Examples of this are most of the organic compounds like benzene and hexane, carbon tetrachloride is also a nonpolar molecule. To identify, you need to look at the structure and the electronegativities of the atoms.