There are two types of matter changes: physical changes and chemical changes. Physical changes alter the physical properties of matter without changing its chemical composition, such as changes in state from solid to liquid to gas. Chemical changes form new chemical substances through rearrangement of atoms, such as burning or rusting. Chemical changes are identified through evidence like gas formation, color change, or energy transfer, and matter is conserved before and after the reaction according to the law of conservation of mass.

1. Changing Matter Matter can be changed two ways: Physically Physical reaction Physical change Chemically Chemical reaction Chemical change

2. Physical Changes Do NOT CHANGE THE TYPE OF MATTER Nothing new or different is formed Could be a change in: Mass Volume Hardness Color Density

3. How to Recognize a Physical Change Change in. . . Size Shape State

4. Examples of Physical Changes Boiling Freezing Dissolving Breaking Making a mixture 2 or more types of matter (substances) mixed together Not in specific amounts Can be separated physically

5. Chemical Properties Describes how a substance reacts Examples: What happens when it’s burned? What happens when it’s mixed with vinegar?

6. Chemical Changes Evidence of a chemical reaction Formation of gas (bubbles form) Formation of precipitate (new substance) Change in color Change in energy (heat and light) Endothermic Absorbs heat energy (gets cold) Exothermic Releases heat energy (gets hot)

7. Examples of a Chemical Change Burning anything Rusting Tarnishing Baking a cake Frying eggs

8. Chemical Changes Atoms are re-arranged, NOT created or destroyed Law of Conservation of Matter Law of Conservation of Mass

9. Chemical Changes Matter is conserved  type of atoms does not change Nothing is created or destroyed Mass is conserved  amount of atoms cannot change Nothing is created or destroyed

10. Chemical Changes To show conservation of mass  Balance equations Make sure there are the same number of each type of atom in the products and in the reactants

11. Balancing Equations The equation for the burning of methane gas in oxygen is: CH 4 + 2 O 2 -> CO 2 + 2 H 2 O Subscript Shows # of atoms Coefficient Shows # of molecules

12. Balanced Equation CH 4 + 2 O 2 -> CO 2 + 2 H 2 O Reactants Products (Original Substances) (New Substances Formed)

13. Types of Chemical Reactions Synthesis Reaction 2 or more simple substances combine to form a more complex substance. A+B  AB Decomposition Reaction A more complex substance breaks down into its more simple parts AB  A + B

14. Types of Chemical Reactions Replacement Reactions AB + CD  AD + C B