1. Phases of Matter and Phase Changes

2. Phase
Depends on strength of forces of attraction between particles. .

3. Solids Definite shape and volume. Most dense phase
Difficult to compress.
Exception is water!.
Particles vibrate in fixed positions
Crystalline lattice structure.
Most attraction between particles.
Note:
Amorphous solids include glass,
plastic, wax, and silly putty

4. Liquids Definite volume No definite shape Hard to compress
Particles slide past each other
Forces of attraction between particles still high

5. Gases No definite shape or volume Expands to fill container
Lowest density
Density depends on pressure
Little attraction between particles
“Vapor” = a gaseous state of something that is normally liquid
(Ex: water vapor)

6. Phases Applet Short Summary video on phases: (1 min)
Applet: (Excellent)

7. Changes in Phase Gas Liquid Solid
Condensation Vaporization (Boiling or Evaporating)
Liquid
Solidification Melting (fusion)
Solid

8. Let’s Skip a Phase Sublimation
Directly from the solid phase to the gas phase.
Happens with substances with weak intermolecular forces of attraction
They separate easily!
Ex: CO2(s) dry ice, Iodine
CO2(s) → CO2 (g)

9. Energy
Energy = capacity to do work or produce heat. It can be anything that causes matter to move or change direction.
Ex: electrical, atomic, mechanical, chemical

10. Law of Conservation of Energy
Energy can’t be created or destroyed, just transferred from one form to another

11. PE vs. KE Potential Energy stored energy
Energy can be stored in bonds between atoms
Kinetic Energy energy of motion
All atoms are moving and vibrating unless at absolute zero

12. Energy and Changes to Matter
Exothermic Change: A + B → C + D + energy
Energy is released or “ex”its
Endothermic Change: A + B + energy → C + D
Energy is absorbed or “en”ters

13. Energy During Phase Changes
Solid Liquid, Liquid Gas
Endothermic
Energy is absorbed and overcomes attractive forces between particles

14. Gas Liquid, Liquid Solid
Exothermic
As particles come closer together energy is released

16. Heat Energy
Also called Thermal energy, it makes particles move more as it is added
Measured in Joules or calories.

17. Heat Flow
Heat energy travels from an object of higher temp. to one of lower temp. until both reach the same temp.

18. Temperature
Measure of the average kinetic energy (motion) of all the particles in a sample.
Not a form of energy!!!
But if you add heat energy or take it away, it causes particles to move faster or slower and thus changes the temp.

19. Heat vs. Temperature Teacup vs. Bathtub Both at 25˚C
Which one contains more heat energy?
Which one has the greater average KE?

20. Label This Graph