1. Phases of Matter
Chapter 3

2. Let’s Review! Matter is… Anything that has mass and takes up space
Can be a pure substance…
Element or compound
Or a mixture…
Homogeneous or heterogeneous
Made of…
Atoms and molecules

3. Kinetic Theory
Energy: the ability to change or move matter, or to do work.
Kinetic Energy: energy of motion
Kinetic Theory of Matter:
ALL matter is made of atoms and molecules
These atoms and molecules act like tiny particles that are always in motion

4. Kinetic Theory
Because all particles of matter are in motion, they all have kinetic energy!
The higher the temperature, the faster the particles move.
At the same temperature, more massive particles move slower than less massive ones

5. Temperature
Particles of matter are constantly moving, but they don’t all move at the same speed, therefore, some have more kinetic energy than others
Temperature: a measure of the average kinetic energy of the particles in an object.

6. Thermal Energy
Thermal Energy: total kinetic energy of the particles that make up a substance
Temperature versus thermal energy
Temperature is average kinetic energy
Thermal energy is determined by the amount of a substance

7. Phases of Matter
Matter can be classified as a solid, liquid, gas, or plasma
This is determined by whether or not the shape and volume are definite or variable

8. Solid
Solid: atoms/molecules can only vibrate in one place, occasionally slide by one another.
students in a detention fidgeting in their seats
Shape: definite
Volume: definite
Energy: low
Crystalline Solid: atoms arranged in a regular repeating pattern
Salt, diamonds
Amorphous Solid: No repeating pattern
Wax, glass

9. Liquid Liquid: atoms/molecules can move about freely
students in the cafeteria
Shape: variable
Volume: definite
Energy: mid-level
Surface Tension: Attraction of molecules at the surface of a liquid
this causes liquids to form spherical drops
Viscosity: resistance to the flow of a liquid
low = runny
high = thicker, like honey

10. Gas
Gas: atoms/molecules move around wildly constantly running into each other.
football practice
Shape: variable
Volume: variable
Energy: High
Because the particles in liquids and gases can move past each other they are considered “fluids”

11. Plasma 4th and most common phase of matter in the universe
Shape: variable
Volume: variable
Energy: highest (the particles are electrically charged)
Affected by magnetic fields

12. Plasma They act like gases but have some differences
plasma can conduct electric current while gases do not
Commonly found in stars, can be created naturally by lightning on Earth and in the hottest part of a very hot flame.

13. Phase Changes
Change of state or a phase change is a conversion of a substance from one phase (solid, liquid, or gas) to another.
The identity of the substance does not change, but the amount of energy does.

14. Phase Changes
Law of Conservation of Mass: Mass cannot be created or destroyed, it is conserved for all physical and chemical changes
Law of Conservation of Energy: Energy cannot be created or destroyed
Energy can change forms during physical or chemical changes, but the total amount present before and after is the same
IF energy of a substance changes it is because it came from another source!

15. Phase Changes
Adding energy, in the form of heat, causes particles to move FASTER
Solid  Liquid  Gas
Removing energy causes particles to move SLOWER
Gas  Liquid  Solid

16. Phase Changes Some phase changes require energy
Melting, evaporation, sublimation
Some phase changes release energy
condensation, deposition
A change in energy often means a change in temperature also

17. Melting
Solid  Liquid
Melting Point: the temperature at which a substance changes from solid to liquid.
Melting point depends on the pressure.

18. Evaporation Liquid  Gas
Boiling Point: the temperature at which a liquid turns into a gas
When humans sweat (a liquid), heat from the body or surroundings causes evaporation
When the water evaporates, the molecules take their heat energy with them, which creates a cooling effect on the body!

19. Sublimation Solid  Gas
Solid carbon dioxide (dry ice) goes from solid to gas
Ice cubes can go from ice to gas while still in the freezer

20. Condensation Gas Liquid
Condensation Point: the temperature at which a gas becomes a liquid
Fog is caused by condensation, the water gas particles clump, energy is released from the particles, and their movement slows down

21. Freezing Liquid  Solid
Freezing Point: temperature at which a liquid becomes a solid

22. Phase Changes
Phase changes can be shown in a graph

23. Phase Changes During a change of state, temperature is constant
The temperature won’t begin to change until the phase change is completed
All of the solid has melted, all of the liquid has evaporated, etc.