1. III) Energy from compounds, Molecules, and atoms

2. A) Chemical Energy

3. 1) all chemical changes involve a change of energy

4. a) A reaction either needs energy or gives off energy

5. b) Chemical energy is a form of potential energy stored in the reactants

6. c) chemical energy usually changes to heat or light energy

7. 2) Molecules are held together by bonds formed by interaction of electrons

8. a) these bonds store chemical energy

9. 3) In some reactions, the products have more chemical energy than the reactants

10. a) Example: When electricity used to separate water into hydrogen and oxygen

11. b) energy is stored in the hydrogen and oxygen molecules

12. 4) In other reactions, the reactants have more chemical energy than the product

13. a) example: burning of fossil fuel releases energy as heat

15. B) Using chemical energy

16. 1) When fuel is burned, combustion causes the chemical bonds to break apart.

17. a) the energy is released as heat

18. b) Almost all the energy used in the United States comes from the burning of fossil

19. 2) Fossil fuels are compounds mode up of carbon and hydrogen atoms

20. a) as the atoms break apart they form bonds with oxygen in the air

21. b) Energy is given off as heat

22. c) Heat is used to heat homes, cook food, or heat water

23. 3) Car engine changes chemical energy of gasoline into kinetic energy

24. a) The gasoline is ignited and causes explosions which move the pistons and in turn the wheels

25. 4) Coal is burned to create electric energy

26. a) The heat creates steam to spin a turbine

27. 5) Batteries contain stored chemical energy

28. a) Connecting the circuit of the battery causes a chemical reaction that changes its chemical energy into electrical energy

29. 6) People get energy from food

30. a) food molecules are broken down as the chemical energy is needed

31. b) fats contain more energy than sugars and proteins do

32. C) Nuclear Energy

33. 1) Nuclear energy is the energy holding protons and neutrons together in the nucleus of an atom

34. 2) Fission: when a nucleus breaks into two parts

35. a) can take place only in very large atoms that can be broken apart easily (like uranium)

36. b) a neutron is shot at a uranium atom and splits the nucleus into two

37. c) This releases large amounts of energy, and two or three neutrons

38. d) the free neutrons hit another uranium atoms and cause a chain reaction

39. 3) Fusion: Nuclei of small atoms fuse together to from larger atoms

40. a) even more energy is produced then fission reactions

41. b) the sun’s energy comes from fusion reactions (two hydrogen combine to form helium)