Chapter 7.1 – Nature of Chemical Reactions

1. 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

2. 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

3. 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

4. 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

5. 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