Definition: Inorganic is a broad term that refers to substances that are not organic in origin. They can be classified into two categories: organic in nature (such as carbohydrates, proteins, lipids) and inorganic in nature (like metals and oxides). Inorganic compounds usually have a chemical formula of [element]2X, where X is the number of atoms present in the compound. Examples include water (H2O), carbonic acid (CO2), aluminum oxide (Al2O3), magnesium silicate (MgSiO4) etc.