1. Chapter 16: Solids, Liquids, and Gases Section 1: Kinetic Theory
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2. Kinetic Theory
Kinetic Theory: the explanation of how particles in matter behave. Based on 3 assumptions:
All matter is composed of small particles.
These particles are in constant, random motion
The particles are colliding with each other and the walls of their container

3. Thermal Energy
Thermal Energy: the total energy of a material’s particles
Even ice has thermal energy!
The tiny water molecules may be packed together, but they are still moving in place (vibrations)
Average Kinetic Energy: the temperature of a substance
When temperature is lower, particles move more slowly
When temperature is higher, particles move more quickly
All particle motion stops at absolute zero (0K) or
-273°C

4. 4 States of Matter: Solid, Liquid, Gas and Plasma
Particles are packed closely together
Most have a specific geometric arrangement (organized)
Have a definite shape and volume
Melting Point: the temperature at which a solid begins to become a liquid

5. Liquids
Liquid:
Particles move past each other, but don’t move far apart—liquids flow
Liquids take the shape of their container, but still have enough attractive force to keep them together
Have no definite shape; have a definite volume
Heat of Fusion: the amount of energy required to change a substance from a solid to a liquid

6. Gases Gas: Particles move quickly and randomly
More collisions than a liquid
Have no definite shape nor volume
Heat of Vaporization: the amount of energy required to change a substance from a liquid to a gas

7. Gases
Boiling point: the temperature at which a liquid’s vapor pressure is equal to the pressure of the atmosphere.
Particles in a liquid gain enough energy that they escape from each other and become a gas.
Depends on atmospheric pressure
Water boils faster at higher elevations
Gases fill their container due to the loss of attractive forces

8. Gases
Diffusion: the spreading of particles throughout a given volume until they are uniformly distributed.
Example: air freshener—eventually spreads throughout the room (the container)
Particles in a liquid gain enough energy that they escape from each other and become a gas.
Depends on atmospheric pressure
Water boils faster at higher elevations
Gases fill their container due to the loss of attractive forces

9. Plasma
Plasma: a gas that has positively and negatively charged particles.
When gases reach extremely high temperatures, like in the sun
Or have high voltage electricity sent through them, like a plasma television
Large collision forces cause the particles to come apart.

10. Heating curve of a liquid

11. Expansion of Matter
Particles move faster and separate as the temperature rises
Thermal expansion: the increase in the size of a substance when the temperature is increased
Occurs in most solids, liquids and gases
Liquid example: a thermometer
Gas example: hot air balloon

12. Water: It’s Different
What happens when you place a can of soda pop in the freezer?
Water expands when it freezes! Why?
Highly positive at one end, highly negative at the other
Charges line up from one particle to another like magnets; causes empty space between particles
Empty space also decreases the density of water ice. Does ice float or sink?

13. Water in all 3 Phases

14. Solid or Liquid? Amorphous solids: “without form” Liquid crystals
Do not have an exact phase change temperature, unlike regular solids
Glass and plastic are examples
Particles are jumbled and twisted, unlike regular solids
Liquid crystals
Flow during the melting phase, but do not lose their ordered arrangement completely
Respond to temperature changes and electric fields, making them useful in displays for clocks & watches, calculators, & video