1. Chapter 10

2. Alpha Decay  Alpha Decay occurs when a nucleus is unstable because it has too many protons  During alpha decay, the nucleus emits Energy (alpha rays) and an Alpha Particle consisting of 2 protons and 2 neutrons (a helium nucleus)  When balancing an alpha decay equation, the total number of protons and neutrons must be the same on both sides of the equation Ex. 210 84 Po 206 82 Pb + 4 2 He + Energy

3. Alpha Decay  When alpha decay occurs, the original atom is reduced by 2 protons, and thus is transformed into an entirely different element  All radioactive decay is dangerous to living things, but alpha decay is the least dangerous as it cannot travel very far or penetrate very deep into the skin

4. Alpha Particles (  ) Radium R 226 88 protons 138 neutrons Radon Rn 222 Note: This is the atomic weight, which is the number of protons plus neutrons 86 protons 136 neutrons + n n p p   He) 2 protons 2 neutrons The alpha-particle  is a Helium nucleus. It’s the same as the element Helium, with the electrons stripped off !

5. Beta Decay  Beta Decay occurs when an unstable nucleus emits Energy (beta rays) and a Beta Particle, which can be either an Electron or a Positron  A Positron is a positively charged electron (or an anti-electron)  The nucleus of the atom either loses a Proton and gains a Neutron (Beta-Plus), or vice versa where it loses a Neutron and gains a Proton (Beta-Minus)

6. Beta Decay  In Beta-Minus decay, a Neutron breaks down into a Proton and an Electron The electron is emitted from the nucleus with the energy that is produced  In Beta-Plus decay, a Proton breaks down into a Neutron and a Positron The positron is emitted from the nucleus with the energy that is produced

7. Beta Particles (  ) Carbon C 14 6 protons 8 neutrons Nitrogen N 14 7 protons 7 neutrons + e-e- electron (beta-particle) We see that one of the neutrons from the C 14 nucleus “converted” into a proton, and an electron was ejected. The remaining nucleus contains 7p and 7n, which is a nitrogen nucleus. In symbolic notation, the following process occurred: n  p + e ( +  Yes, the same neutrino we saw previously

8. Gamma Decay  In Gamma Decay, only energy in the form of gamma rays is emitted  Gamma decay occurs when a nucleus is in an excited state and needs to get rid of energy to be stable again  Because only energy is emitted during gamma decay, the number of protons remains the same and the atom does not become a different element

9. Gamma particles (  ) In much the same way that electrons in atoms can be in an excited state, so can a nucleus. Neon Ne 20 10 protons 10 neutrons (in excited state) 10 protons 10 neutrons (lowest energy state) + gamma Neon Ne 20 A gamma is a high energy light particle. It is NOT visible by your naked eye because it is not in the visible part of the EM spectrum. A gamma is a high energy light particle. It is NOT visible by your naked eye because it is not in the visible part of the EM spectrum.

10. Electromagnetic Waves ALPHA RAYS Can travel only a few centimeters through air Can burn the skin, but not penetrate it BETA RAYS Can travel up to a meter through air Can penetrate the skin and damage the dermis GAMMA RAYS Can travel thousands of meters through air Can penetrate and damage cells deep within the body

11. Electromagnetic Waves  Gamma rays are electromagnetic waves that carry photons of energy called Gamma particles  Photons are tiny “packets” that are used to transfer energy though space  They travel through space at the speed of light  Gamma rays have the most energy of all electromagnetic waves, and so are the most harmful to living things

12. Three Common Types of Radioactive Emissions - Penetrability Alpha particles may be completely stopped by a sheet of paper, beta particles by aluminum shielding. Gamma rays, however, can only be reduced by much more substantial obstacles, such as a very thick piece of lead.