1. Nuclear Reactions Powering the Sun since 4.6 Billion B.C.

2. Nuclear Reactions Occur when the nucleus of an atom is changed Nuclear Reactions release the most energy of any type of reactions. http://education.jlab.org/qa/atom_model_03.gif Nucleus

3. Fission When a large nucleus is split into two or more smaller nuclei Only certain elements’ nuclei will fission, or split Uranium & plutonium are the most common fissionable elements http://holvoet.free.fr/Voyage/energy/img/fission_v.gif

4. Fission Nuclear Chain Reaction  When one fission reaction sets off several other fission reactions, which each set off new fission reactions. http://wps.prenhall.com/wps/media/objects/476/488316/Instructor_Resources/Chapter_17/FG17_10.JPG

5. What happens during a fission reaction? http://www.oup.co.uk/images/oxed/children/yoes/atoms/fission.jpg 1. A large nucleus is hit with a neutron. Nucleus: U or Pu Neutron

6. What happens during a fission reaction? http://www.oup.co.uk/images/oxed/children/yoes/atoms/fission.jpg 2. The neutron makes the nucleus of the atom split. Nucleus: U or Pu Neutron

7. What happens during a fission reaction? http://www.oup.co.uk/images/oxed/children/yoes/atoms/fission.jpg 3. Large amounts of energy are released when it splits Nucleus: U or Pu Neutron

8. What happens during a fission reaction? http://www.oup.co.uk/images/oxed/children/yoes/atoms/fission.jpg 4. A few neutrons are sent flying from the split nucleus. These neutrons start new fission reactions Nucleus: U or Pu Neutron Neutrons Gamma Ray

9. Fission Critical mass  The smallest amount of uranium or plutonium that is needed to start a chain reaction. The critical mass for Uranium is around 33 pounds.

10. Fusion When two small nuclei join together to form a larger nucleus Fusion releases much more energy than fission

11. What Happens in a Fusion Reaction? 1.Two hydrogen nuclei smash together at very high speeds Hydrogen-2 (Dueterium) Hydrogen-3 (Tritium) 2.The hydrogen nuclei stick together (or fuse) to make a larger nucleus 3.Huge amounts of energy are released Helium neutron http://www.generalfusion.com/images/reaction2.gif

12. Where does fusion happen? Occurs in the Sun and other stars Fusion bombs (H-bombs)