1. Phases of Matter and Phase Changes
Unit 7
Chapter 13

2. Phases of Matter Liquids and Solids
Molecular Level Comparison of Gases, Liquids and Solids.

3. Liquid Properties
Molecular Motion -Kinetic-molecular theory predicts the constant motion of the liquid particles
Individual liquid molecules do not have fixed positions in the liquid.
Volume - Forces of attraction between liquid particles limit their range of motion so that the particles remain closely packed in a fixed volume.
Shape - Liquids can take the shape of their container

4. Properties of Liquids
Density - Like gases, liquids can be compressed. But the change in volume for liquids is much smaller because liquid particles are already tightly packed together.
Diffusion - A liquid diffuses (mix) more slowly than a gas at the same temperature, however, because intermolecular attractions interfere with the flow.

5. Properties of Solids Exist in ordered patterns
Most solids have a crystalline shape repeated over and over
Exception: Glass (considered an amorphous solid, which means that the molecules are in stuck in random positions
Molecular Motion - Particles are in fixed positions so they just vibrate in place.
Diffusion - Cannot diffuse (cannot mix spontaneously with other solids)

6. More Solid Properties
Density - The particles in a solid are more closely packed than those in a liquid.
Solids are usually the most dense of the three states Exception: Water
Cannot be compressed – therefore they have fixed volumes.

7. Changes In State Solid Liquid Gas Freezing Sublimation Deposition
Melting
Vaporization
Liquid
Gas
Condensation

8. Exothermic vs. Endothermic
Exothermic Change – Heat Energy is released to the surroundings.
Molecules slow down, extra energy is transferred to surrounding.
Cooling phase changes are exothermic
Endothermic Change – Heat energy is absorbed by the system
-Molecules move faster as they absorb energy
-Phase changes that require energy (or heat) are endothermic

9. Heating & Cooling Curve For a Pure Substance
Boiling/condensation Temperature
Vaporization
Liquid and gas
Gas heats
Temperature oC
Melting
Solid & Liquid
Liquid heats
Solid heating
Melting/Freezing Temperature
Energy Added

10. Another graphic