1. 3.3 Phase Changes What are six common phase changes?
What happens to a substance’s temperature and a system’s energy during a phase change?
How does the arrangement of water molecules change during melting and freezing?
How are evaporation and boiling different?

2. 3.3 Phase Changes
Characteristics of Phase Changes A. One way to recognize a phase change is by measuring the temperature of the substance. B. Temperature DOES NOT change during a phase change.

3. 3.3 Phase Changes
C. Energy is either absorbed or released during a phase change. 1. Endothermic change- energy is absorbed from its surroundings. 2. Exothermic change- energy is released to the surroundings.

4. 3.3 Phase Changes
Gas
Solid Liquid

5. 3.3 Phase Changes Gas Solid Liquid Melting- endothermic
Molecules gain energy from the surroundings, overcome attractions and move from their fixed position.

6. 3.3 Phase Changes Gas Solid Liquid Vaporization- endothermic
VVa
Vaporization- endothermic
Molecules move faster and farther apart. Molecules become more disordered.

7. 3.2 Changes of Matter Gas Solid Liquid Sublimation- endothermic
Molecules move very quickly and far apart. Needs energy
Dry Ice, Snow bank

8. 3.2 Changes of Matter Gas Solid Liquid Condensation- exothermic
Molecules slow down and
become more ordered and
release energy.

9. 3.2 Changes of Matter Gas Solid Liquid Freezing- exothermic
Molecules become more ordered, slow down, clump together, releases energy

10. 3.3 Phase Changes Gas Solid Liquid Molecules become more ordered,
Deposition- exothermic
Frost on a window
release energy

11. 3.3 Phase Changes
Heat Energy
Temperature

12. 3.3 Phase Changes
Assignment: