1. Thermal Expansion & Contraction Changes of State

2. What have we learned about so far?
Turn to the person beside you and tell them 3 things you learned last class.
We learned about…
Matter, Mass & Volume
Three states of matter (solid, liquid gas)
Particle model and the Kinetic Molecular Theory

3. Thermal Expansion and Contraction
Kinetic Energy (KE) is the energy of motion.
When you add energy to something, you increase the KE.
One way to add energy to an object is to add HEAT.
Adding heat makes particles:
A) move FASTER,
B) cover more area and
C) the material EXPANDS in volume!
This process is called…. Thermal Expansion

4. Thermal Expansion and Contraction
Thermal expansion: the INCREASE in volume of a substance when its temperature is raised.
Thermal contraction: the DECREASE in volume of a substance when its temperature is lowered.
Can you use the concepts of thermal expansion and contraction to explain how a thermometer works?

5. Thermal Expansion and Contraction
In thermal contraction particles slow down and take up less space.
There is one exception to thermal contraction can you guess what it is?
WATER! When water cools and freezes it expands!

6. Changes of State

7. Changes of State
Melting Point: the temperature at which solid turns to liquid.
Boiling Point: the temperature at which liquid turns into gas.

8. Changes of State Name Change of State (from _ to _)
Heat Gained or Lost?
Example:
Melting
Solid to liquid
Evaporation
Liquid to gas
Condensation
Gas to liquid
Solidification
Liquid to solid
Sublimation
Solid to gas
Deposition
Gas to solid

9. Changes of State Name Change of State (from _ to _)
Heat Gained or Lost?
Example:
Melting
Solid to liquid
Gain
Evaporation
Liquid to gas
Condensation
Gas to liquid
Lost
Solidification
Liquid to solid
Sublimation
Solid to gas
Deposition
Gas to solid

10. Changes of State Name Change of State (from _ to _)
Heat Gained or Lost?
Example:
Melting
Solid to liquid
Gain
Ice to water
Evaporation
Liquid to gas
Water turning to steam
Condensation
Gas to liquid
Lost
Water on a cold glass of water
Solidification
Liquid to solid
Water turning to ice
Sublimation
Solid to gas
Dry ice
Deposition
Gas to solid
Frost on a windshield

11. Thermal Expansion & Contraction