1. Kinetic Molecular Theory and States of Matter

2. Kinetic Theory of Matter
Particles (molecules) are in constant motion
The amount of kinetic energy determines the phase of the sample
Temperature is a measure of average kinetic energy
High kinetic energy = faster movement and bigger movement of particles
Large distances between gas particles makes attractions between particles unimportant
Strong attractions in solid and liquid phases make samples dense, not compressible

3. The Kinetic Theory
1. All matter is composed of small particles (atoms, molecules, or ions).
2. They are in constant, random motion.
3. They constantly collide with each other and with the walls of their container.

4. Thermal E x p a n s i o n
Particles in any state expand when heated Expansion joints (solid)
Mercury is a liquid that expands in thermometers
Air expands when heated (becoming less dense)

5. STATES OF MATTER Defined by particle arrangement
Defined by kinetic energy of particles
Defined by distance between particles

6. Solids Fixed Volume Fixed Shape Not Compressible Very Dense
Particles are tightly packed in an orderly arrangement, little space between particles
Very strong forces of attraction between particles
Particles vibrate about a fixed position
Lowest energy particles

7. Liquids Fixed Volume Take the shape of the container Not Compressible
Dense
Particles are closely packed in a disorderly arrangement, spacing is far enough to slide past
Strong forces of attraction between particles
Particles can move past one another; Liquids flow
Middle energy particles

8. Gases Not Fixed Volume Take the shape of the container
Easily Compressible
Not Dense
Particles are far apart in random arrangement
Forces of attraction between particles are negligible
Particles move about randomly at high speed
Highest energy particles

9. STATES OF MATTER LIQUID PLASMA SOLID GAS
Tightly packed, in a regular pattern
Vibrate, but do not move from place to place
Close together with no regular arrangement.
Vibrate, move about, and slide past each other
Well separated with no regular arrangement.
Vibrate and move freely at high speeds
Has no definite volume or shape and is composed of electrical charged particles

10. Phase Changes

11. Energy of Phase Changes

12. Phase Change Diagram

13. Phase Diagrams

14. Phase Diagram

15. Learning Check
Identify the solid, liquid, and gas phases on the phase diagram.

16. Learning Check
What are the melting point and the boiling point of the substance at 1atm?

17. Learning Check
What phase is the sample at 1 atm and 110oC?

18. Learning Check
What would cause the sample to change from a liquid to the solid phase at constant temperature?

19. Temperature and Phase Changes
What happens to the temperature of the sample during a phase change?

20. Thermodynamic Properties