1. Nuclear Reactions

2. Standards Know that some atomic nuclei can change, including:
Spontaneous decay
Fission
Fusion
Alpha, beta & gamma radiation

3. Types of Nuclear Reactions
Natural Radioactive Decay
Nuclear Fission
Nuclear Fusion

4. Natural Radioactive Decay
Occurs naturally in some elements, especially heavy elements (atomic #83 & higher)
Nucleus breaks down naturally, releasing particles & energy
Used for radioactive dating

5. Types of Natural Radioactive Decay
3 most common types of radioactive decay
Alpha decay
Beta decay
Gamma decay

6. Types of Natural Radioactive Decay
Alpha decay – an alpha (α) particle is emitted from the nucleus.
Alpha particle has 2 p+ & 2 n0 (same as a helium nucleus)
Least energetic of the 3, can be blocked by a piece of paper or surface of skin

7. Types of Natural Radioactive Decay
Beta decay - a beta () particle is emitted from the nucleus.
Beta particle is an e- formed from decomposition of a n0 into a p+ & e-
Can be stopped by aluminum foil or thin wood

8. Types of Natural Radioactive Decay
Gamma decay – emission of a high energy photon (particle of light)
Will only be stopped by several meters of concrete or several centimeters of lead
Will pass through human body and are very dangerous

9. Each type of radiation can penetrate materials differently

10. Nuclear Fission
Heavy element decays (nucleus splits), releasing particles (n0) and large amounts of energy
1st atomic bombs were fission bombs:
Little Boy (fission of uranium) – dropped on Hiroshima,
Fat Man (fission of plutonium) – dropped on Nagasaki
Present-day nuclear power plants work by fission

11. Fat Man
Little Boy
Nagasaki

12. Nuclear Fusion
Nuclei of small atoms combine to form a larger nucleus (usually hydrogen nuclei combine to form helium), releasing huge amounts of energy in the process
Core of our sun is a fusion reactor
Appealing as energy source, but difficult to achieve high temperatures necessary and to contain reaction
Much safer than fission reactors

13. Our Sun photo: SOHO
Tokamak (fusion reactor)