1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. PHYSICAL SCIENCE sixth edition Bill W. Tillery Chapter 13 Nuclear Reactions

2. ParticleCompositionChargePenetration Alphaα 2 protons and 2 neutrons 2+ stopped by paper Betaβ an electron 1- stopped by aluminum Gammaγ pure energy 0 stopped by lead Radioactive particles

3. Relative penetrating abilities of alpha, beta, and gamma radiation

4. nucleus Proton and neutron called “nucleons”

5. Atomic number (Z) = number of protons in nucleus Mass number (A) = number of protons + number of neutrons = atomic number (Z) + number of neutrons Isotopes - atoms of the same element (X) with different numbers of neutrons in their nuclei X A Z U 235 92 U 238 92 Mass Number Atomic Number Element Symbol

6. Origins of Radiation Exposure in the US Natural background (81%): Biggest source: Radon-222 Medicine (15%)Consumer products (4%) Can’t see it Can’t smell it Can’t taste it Can’t hear it Can’t feel it

7. Chemically inert, uncharged noble gas Produced from decay of uranium-238 Seeps out of rocks and soil Builds up indoors and in mines T 1/2 is 3.8 days Decays by alpha particle emission Produces short-lived solid alpha-emitters - Polonium 218 and 214 Radon-222

8. Zone 1 (red zones)Highest Potential Zone 2 (orange zones)Moderate Potential Zone 3 (yellow zones)Low Potential

9. Biological Effects of Radiation Radiation absorbed dose (rad) Roentgen equivalent for man (rem) Units of Radiation Devices to measure radiation Geiger counter Personal dosimeters

10. Fig. 13.11 Working parts of a Geiger counter

11. Table 10.1