1. Forming New Substancesp

2. Chemical Changes
A chemical reaction is when one or more substances change to make one or more new substances.
Any time there is a chemical change, a chemical reaction has occurred.

3. CLUES TO CHEMICAL CHANGES
Bubbling - a new gas is formed

4. CLUES TO CHEMICAL CHANGES
2. Solid formation- a precipitate is formed
A precipitate is a solid that is insoluble in the reaction mixture

5. CLUES TO CHEMICAL CHANGES
3. Change in color – a new substance is forming

6. CLUES TO CHEMICAL CHANGES
4. Energy change – energy is being released or absorbed

7. How Can You Be sure that a Chemical Reaction is Occurring?
The most important sign is the formation of new substances that have new properties.
The properties of the new substances are very different from the properties of the starting substances.

8. CHEMICAL BONDS
A chemical bond is a force that holds atoms together in a molecule.
For a chemical reaction to occur the bonds in the starting substances must break, the atoms must rearrange and new bonds form to make new substances.