Chemistry: CHEMICAL SUBSTANCES
Chemical substance is that substance that tells us about the chemical composition of a material. The concept was introduced and popularized in the eighteenth century by Joseph Proust; when he was working on the composition of copper carbonate. He was able to deduce the law of constant composition which says all compounds with same molecular mass have similar composition of mass. Chemical substances are ordinary substances that we use in our daily life. Anything that is made up of two or more elements or compounds is known as a chemical substance. For example, the water we drink is also a chemical substance. The chemical formula of water is h2O, which means it contains two molecules of hydrogen and I molecule of oxygen.
Chemical substances are those substances that take part in a reaction. You may have come across with some substances that rust when kept in the present of air and humidity; it is because they are chemical substances and undergo a chemical reaction in presence of right pressure, humidity and catalysts. All those substances that do not take part in a chemical reaction do not come under chemical substances and are often called neutral elements. The substances react with each other in order to satisfy the deficiency of electrons in the outer shell and reach a stable state where they no longer react with each other. For example carbon and oxygen when present together will react to form carbon dioxide but when you keep molecules of carbon dioxide together they will not react with each other as they have already stabilized themselves by combining with each other.