1. Chemical Reactions

2. What is a chemical reaction?
A chemical reaction is the process by which substances undergo change to produce different substances
These new substances have different properties from the original substances

3. Clues to chemical reactions
Gas Formation
Solid Formation
Color change
Energy change

5. Breaking and making bonds
New substances are formed in chemical reactions because chemical bonds are broken, atoms rearranged, and new bonds form to form new substances

6. Chemical formulas Shorthand notation for a chemical compound
Includes subscripts – number written below and to the right of the symbol to let you know the number of elements present

7. Chemical equations
Shorthand description of a chemical reaction

8. Reacts yield products
Reactants – starting materials in a chemical reaction
Products – substances formed from a reaction
Coefficient – number placed in front of a chemical symbol or formula

9. Type of Reaction Definition
A = Red B = Blue C = Green D = Yellow
Type of Reaction
Definition
Equation
Synthesis
Decomposition
Single Replacement
Double Replacement
Two or more elements or compounds combine to make a more complex substance
A + B → AB
Compounds break down
into simpler substances
AB → A + B
Occurs when one element replaces another one in a compound
AB + C → AC + B
AB + CD → AC + BD
Occurs when different atoms in two different compounds trade places

10. Law of Conservation of Mass
Mass is neither created nor destroyed in ordinary chemical and physical changes
A chemical equation must show the same number and kind of atom on both sides of the arrow

11. Energy released in exothermic reactions
Exo means “exit” and thermic means “heat” or “energy”
EXAMPLES:
Glow sticks
Flashlight
Campfire
Fireworks

12. Energy is absorbed in endothermic reactions
Endo means “go in” and thermic means “heat” or “energy”
Examples
Ice pack

13. Energy is conserved – It's a LAW!
Energy can be neither created nor destroyed