1. Changes in States of Matter
Chapter 6 Lesson 2

2. Solids, liquids and gases
We have learned a little about the three states of matter that exist mainly on earth. What do we know about them so far?

3. How can a solid ice cube change into liquid water?
Ice and liquid water are different states of the same substance. They are both made from atoms that join to become water molecules (H2O). What makes it change from one state of matter to another?

4. Changes in energy can cause matter to change from one state to another
Example: Changes in the weather can cause changes in states of matter. In early spring, a solid icicle melts into liquid water.

5. When energy such as heat is added to one state of matter, it can result in a different state of matter

6. Thermal energy
Thermal energy deals with the transfer of heat. Heat can be transferred by radiation, conduction, and convection.

7. Why do you feel cold when you touch ice?

8. Thermal energy
When you touch ice, the heat from your hand is transferred to the ice making the ice melt and your hand feel cold.

9. When heat is added or taken away from a substance what happens to the motion of the particles?
A state of matter can change when the temperature changes. As the temperature rises particles move to a more active state; and when heat is taken away the motion of the particles slow down. If energy is added (like increasing the temperature) or if energy is taken away (like freezing something) you have created a physical change.

10. What exactly is the sun doing to the particles in this icicle?
It is adding heat. Adding heat will result in:
changes in the motion of the particles.
strength of the forces among particles.

11. Heat makes atoms and molecules (particles) move faster

12. When atoms and molecules move faster they have more kinetic energy
What is kinetic energy? Kinetic energy is the energy of motion. Simply put: moving energy

13. Which do you think has more kinetic energy?
ice cubes
water

14. Temperature is a measure of the average kinetic energy of the particles in a material

15. Melting Point
Now you're a solid. You're a cube of ice sitting on a counter. You dream of becoming liquid water. You need some energy. The easiest energy around is probably heat. There is a magic temperature for every substance called the melting point. The melting point is the temperature at which a solid changes to a liquid.

16. Freezing point - the temperature at which a liquid changes to a solid

17. Boiling point – temperature at which boiling occurs in a liquid

18. vaporization
The change from a liquid to a gas is called vaporization

19. condensation
The change from a gas to a liquid.

20. Sublimation
The change of a solid to a gas without going through the liquid state. For sublimation to occur, thermal energy must be added to a solid.

21. deposition
The change of a gas to a solid without going through the liquid state. For deposition to occur, thermal energy must be removed from a gas.