1. Changes in Matter 2.3 PHYSICAL CHANGE
-a substance that undergoes a physical change is still the same substance after the change
-changes of state
-solid, liquid, gas
-changes in shape or form
-dissolving, bending, crushing, breaking, chopping, etc.

2. CHEMICAL CHANGE
-produces one or more new substances
-combustion, electrolysis, oxidation, tarnishing
MATTER & THERMAL ENERGY
-every physical or chemical change includes a change in energy
-endothermic changes
-exothermic changes

3. Chemical Change - Changes in Matter
A change in matter that produces one or more new substances is a chemical change, or a chemical reaction.

4. Conserving Matter
The idea of atoms explains the law of conservation of matter. For every molecule of methane that burns, two molecules of oxygen are used. The atoms are rearranged in the reaction, but they do not disappear.

5. Comparing Energy Changes
- Changes in Matter
Comparing Energy Changes
A student observes two different chemical reactions, one in beaker A, and the other in beaker B. The student measures the temperature of each reaction every minute. The student then plots the time and temperature data and creates the following graph.

6. Comparing Energy Changes
- Changes in Matter
Comparing Energy Changes
Reading Graphs:
What do the numbers on the x-axis tell you about the length of the experiment?
The experiment lasted for 10 minutes.

7. Comparing Energy Changes
- Changes in Matter
Comparing Energy Changes
Comparing and Contrasting:
How did the change in temperature in beaker B differ from that in beaker A?
The temperature decreased in beaker B, but increased in beaker A.

8. Comparing Energy Changes
- Changes in Matter
Comparing Energy Changes
Interpreting Data:
Which reaction is exothermic? Explain your reasoning.
Reaction A is exothermic because thermal energy was released, causing an increase in temperature.

9. Comparing Energy Changes
- Changes in Matter
Comparing Energy Changes
Calculating:
Which reaction results in a greater change in temperature over time?
Reaction A

10. Relating Cause and Effect
A cause makes something happen. An effect is what happens. As you read, identify two effects caused by a chemical change. Write the information in a graphic organizer like the one below.
Cause
Effects
A single substance changes to one or more other substances.
Chemical change
Two or more substances combine to form different substances.