Why are some molecues polar and nonpolar?

Answer 1

In chemistry, as you will learn, atoms, aside from having Protons and Neutrons and Electrons, also have a property called 'electronegativity'. Electronegativity of an atom affects how it gives and takes electrons. So based on where the atoms with the most and least electronegativity level are placed will determine where the most electrons are. The end with the most electrons will be negative, and the other end positive. This how a polar molecule works.

In a nonpolar molecule, like Ammonia (NH3) most of the atoms are the same, and thus have the same electronegativity levels (three Hydrogen atoms). These are arranged around one particularly electronegative atom (Nitrogen) so all the electrons are distributed evenly, thus a lack of electromagnetic poles.

Answer 2

Molecules can be polar or nonpolar depending on the distribution of charge in the molecule. In polar molecules, there is an uneven distribution of electrons leading to a partial positive and negative charge. Nonpolar molecules have an even distribution of electrons, resulting in no distinct positive or negative regions.