This chapter introduces the concept of chemical reactions —the processes in which one or more substances (reactants) are transformed into new substances (products). It explains how these reactions are represented using chemical equations , and emphasizes the importance of balancing equations to obey the Law of Conservation of Mass . Students learn to identify different types of chemical reactions such as: Combination Reactions – where two or more substances combine to form a single product. Decomposition Reactions – where a single compound breaks down into simpler substances. Displacement and Double Displacement Reactions – where elements or ions are exchanged. Redox Reactions – involving oxidation and reduction processes.