1. Thermal Energy & Heat Chapter 2 Section 3 5. Reactions
a. Students know reactant atoms and molecules interact to form products with different chemical properties.
b. Students know the idea of atoms explains the conservation of matter: In chemical reactions the number of atoms stays the same no matter how they are arranged, so their total mass stays the same.
c. Students know chemical reactions usually liberate heat or absorb heat.
d. Students know physical processes include freezing and boiling, in which a material changes form with no chemical reaction.
Chapter 2 Section 3

2. Energy
What are four types of Energy? What is the SI unit for Energy? Energy: The ability to do WORK or cause change Law of Conservation of Energy: Energy is transformed. Energy is never created of destroyed

3. Thermal Energy
Thermal Energy: - TOTAL kinetic energy of all the particles - When you describe matter as hot or cold. - Flows from warmer to colder matter. Simply put, thermal energy is kinetic energy at the molecular level. Temperature: Measurement of average energy of the motion of these particles. (Fahrenheit, Celsius, Higher Temp = particles move Lower Temp = particles move slower

4. What is heat? What is cold?
What direction does heat always flow?

5. Endothermic Change vs. Exothermic Change
Endothermic Change: Energy is taken in, or absorbed from surrounding matter. Example: Ice Melting Exothermic Change: Energy is released Example: Fire releases energy in form of heat

6. Endo- or Exo-? Is heat given off? Exothermic or
Is heat taken away? Endothermic
Making Ice Cubes (Liquid to Solid)
Baking Bread
Cooking an Egg
A Burning Candle
Dew Forming on Grass (Gas to Liquid)
Burning Fuel (Liquid to Gas)
Condensation (Gas to Liquid)
Melting Butter (Solid to Liquid)

7. Chemical Energy
Chemical Energy: The energy stored in chemical bonds between atoms Stored in Food, Gasoline, Human Body. . . When a chemical change occurs (example), chemical bonds are broken and new bonds are formed.
Every bond has a certain amount of energy. To break the bond requires energy -- in chemical language it is called endothermic. These broken bonds then join together to create new molecules, and in the process release heat -- chemists call this exothermic.

8. Electromagnetic Energy
A form of energy that travels through space as waves.
Most notably, the sun!
Radio waves, infrared rays (heat lamps), microwave oven, cellphones, UV rays, X-rays, WiFI. . . Waves are everywhere!

9. Electrical Energy
The energy of electrically charged particles moving from one place to another
Electrolysis:
A chemical change with electrical energy that produces new substances

10. Vocabulary Check!

11. Example

12. Questions
From where does the energy to heat water for hot chocolate originally come?
Make a flow chart that traces the path that energy takes when you heat water for hot chocolate.
On your flow chart, identify the form that energy takes at each step along the path.
Was any energy lost during the energy transformations that heated the water for hot chocolate?