Chapter 7.1 – Nature of Chemical Reactions What do you think of when you hear chemical reaction? chemical reaction – when a substance undergoes a chemical change to form a new substance

Chapter 7.1 – Nature of Chemical Reactions chemical reactions have two parts reactant – substance that changes in a chemical reaction product – substance that forms in a chemical reaction reactants make products

Chapter 7.1 – Nature of Chemical Reactions chemical reactions always involve changes in energy - to break chemical bonds energy must be added the energy can be heat, electricity, sound, or light when chemical bonds are formed energy is released chemical energy – energy stored in chemical bonds - released when a chemical compound reacts

Chapter 7.1 – Nature of Chemical Reactions in chemical reactions energy is conserved the total energy of the reactants equals the total energy of the products the energy in a chemical reaction can change form exothermic reaction – chemical reaction where energy is released to the surroundings as heat

Chapter 7.1 – Nature of Chemical Reactions endothermic reaction – chemical reaction where energy is absorbed and stored in the products as chemical energy photosynthesis is endothermic