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