Compound is a substance that is made out of two or more elements. For example, H2 (Hydrogen Gas), NaCl (Sodium Chloride; Table salt), Cl2 (Chlorine Gas), H2O2 (Hydrogen Peroxide) By these simple definitions, you should be able to decide whether water (H2O) is a compound or not.Water molecules are made up of two elements: hydrogen and oxygen. They are connected in the case of water, but they can be separated through Electrolysis of water. Of course, water in modern times is known as a compound of 2 H and 1 O. Water has special properties.