1. MRS. BROSTROM INTEGRATED SCIENCE CHEMICAL REACTIONS UNIT 4

2. FORMING NEW SUBSTANCES A chemical reaction is a process in which one or more substances to make one or more new substances Chemical and physical properties differ from the original substance For example: mixing baking powder and water form CO 2 and give muffins there sponge-like texture

3. HOW CAN YOU TELL THAT A CHEMICAL REACTION IS TAKING PLACE? Gas formation Solid formation- a precipitate is a solid substance that is formed in a solution Energy exchange- energy is released as light or heat or energy can be absorbed Color change

4. THE SUGAR SNAKE However, these signs do not guarantee a chemical reaction is taking place The most important sign is the formation of new substances that have different properties For example, combining sugar and sulfuric acid; bubbles form, a gas is given off, and the beaker becomes hot But most important, a new substance is formed with different properties

5. BREAKING AND MAKING BONDS A chemical bond is a force that holds two atoms together in a molecule For a chemical reaction to take place, the original bond must break and new bonds must form 1.If molecules bump into each other with enough energy 2.The chemical bond breaks 3.The atoms rearrange to make new substances

6. NEW BONDS MAKE NEW SUBSTANCES Sodium is a metal that reacts violently in water Chlorine gas is poisonous But when Na and Cl react, they result in a new substance, NaCl or salt Salt is a harmless substance with very different properties + 