Polar molecules occur when two atoms do not share electrons equally in a covalent bond. A dipole forms, with part of the molecule carrying a slight positive charge and the other part carrying a slight negative charge. This happens when there is a difference between the electronegativity of each atom. An extreme difference forms an ionic bond, while a lesser difference forms a polar covalent bond.
Examples of polar molecules include:
Water - H2O
Ammonia - NH3
Sulfur dioxide - SO2
Hydrogen sulfide - H2S
Ethanol - C2H6O
