Nuclear Radiation

1. Nuclear Radiation (c) Douglas E. Raynie, South Dakota State University, 2002

2. Natural Radioactivity: • Isotopes of some elements may have unstable nuclei. • They will spontaneously (naturally) emit energy to become more stable. • They are RADIOACTIVE. • Elements greater than atomic number 84 are all radioactive. (c) Douglas E. Raynie, South Dakota State University, 2002

3. 14 6 C Writing Isotopes Atomic Mass (sum of protons and neutrons) Element = carbon Atomic Mass = 14 # of protons = 6 # of neutrons = 8 Atomic Number (# of protons)

4. 141 58 Ce Your Turn Element = Atomic Mass = # of protons = # of neutrons =

5. Types of Radiation • Alpha Particles • Beta Particles • Gamma rays

6. ALPHA (a) PARTICLE • identical to heliumnucleus. • has 2 protons and 2 neutrons

7. BETA (b) PARTICLE • is a high-energy • electron, so it has a negative charge and • mass number of 0.

8. Gamma Emitters: • Atomic number and mass number do not change since gamma radiation consists of energy, not mass.

9. (c) Douglas E. Raynie, South Dakota State University, 2002

10. Radioactive Isotopes: • TRANSMUTATION is the process of changing one element into another. • A stable atom can be bombarded with fast-moving a particles, protons, or neutrons. • A radioactive isotope is called a RADIOISOTOPE (c) Douglas E. Raynie, South Dakota State University, 2002

11. (c) Douglas E. Raynie, South Dakota State University, 2002

12. Half-Life: • The HALF-LIFE of a radioisotope is the amount of time it takes for half of the sample to decay. • A DECAY CURVE is a graph of the decay of a radioisotope (amount vs. time). (c) Douglas E. Raynie, South Dakota State University, 2002

13. Half-life: • By knowing the half-life, we can do lots of • important things, like: • Carbon dating of fossils • Medical diagnosis • Predict the fate of nuclear waste (c) Douglas E. Raynie, South Dakota State University, 2002

14. (c) Douglas E. Raynie, South Dakota State University, 2002

15. Fission and Fusion:

16. Fission • The splitting a big atom into two smaller atoms by bombarding with neutrons. (c) Douglas E. Raynie, South Dakota State University, 2002

17. Chain Reaction: • The fission process can continue until all of the available “big atoms” are gone. • This is a CHAIN REACTION. (c) Douglas E. Raynie, South Dakota State University, 2002

18. Why is energy released? • Just like a chemical equation, a nuclear equation shows reactants and products.

19. …Some mass is lost… • It just so happens, the mass of the products is slightly less than the mass of the reactants! Before After Slightly less mass

20. Einstein tells us …E = mc2 Energy = Mass x (Speed of Light)2 Energy = Mass x (300,000 km per second)2 • Therefore… • One kg of mass converted to energy, has the same explosive power as 8 million tons of TNT

21. Nuclear Power: • This is a fission reaction. • How they work… that’s for another time... (c) Douglas E. Raynie, South Dakota State University, 2002

22. Nuclear Power: Fission is the process that creates steam in our current nuclear power plants Nuclear waste: The products of fission reactions are unstable, and highly radioactive. Because of its long half-life, some nuclear waste must be kept from entering the environment for 100,000 years or more. (c) Douglas E. Raynie, South Dakota State University, 2002

23. Fusion: • FUSION is the combining of two small atoms into one bigger atom with the release of energy. • More energy is released than fission. (c) Douglas E. Raynie, South Dakota State University, 2002

24. Fusion