# Chapter 19 Lecture Outline

## Diagnosing Appendicitis

1. Nuclear Particles
2.  Name Symbol Symbol Mass Charge Alpha [alpha] 4He 4 +2 Beta [beta] 1-e 0 -1 Gamma [gamma] 0 0, radiation (light) Neutron n 1 0 Proton p 1H 1 +1 Positron +1e +[beta] 0 +1

1. Alpha emission: 238U -> 234Th + 4He

2. Beta Emission:
1. 14C -> 14N + -1e
2. 1n -> 1p + -1e (neutron -> proton + electron)

3. Positron Emission
1. 11C -> 11B + +1e
2. 1p -> 1n + +1e (proton -> neutron + positron)

4. Electron Capture
1. 40K + -1e -> 40Ar
2. 1p + -1e -> 1n (proton + electron -> neutron)

## The Valley of Stability: Predicting the Type of Radioactivity

Nuclear Stability. Likelihood that isotope is radioactive depends upon:
1. >83 protons are unstable
2. Magic Numbers 2, 8, 20, 28, 50, 82 are stable. If magic number of both protons and neutrons, then "double magic"
3. Even numbers of neutrons or protons are stable.
1. Both even, most stable
2. One even one odd, less stable
3. both odd, least stable

4. Belt of stability
1. If above, then decay to convert a neutron to a proton.
2. If below, then positron emission (or electron capture) to convert a proton to a neutron.

1. Half life of radioactive isotopes
1. Radioactive decay is first order
2. First order rate law
1. For half life t1/2 = 0.693/k
2. Amount remaining after time t

1. 238U Dating (Age of Rock Problem from Page 907)
1. 238U -> 206Pb t1/2 = 4.5*109 years
2. 40K Dating
1. 40K + -1e -> 40Ar t1/2 = 1.3x109 years
3. 14C Dating
1. 14N + 1n -> 14C + 1H
2. 14C -> -1e + 14N t1/2 = 5730 years
3. Shroud of Turin (Dated at 1300 AD). Determine 14C present. What would it be if 0 AD?

## The Effects of Radiation on Life

Production of New Nuclei
1. Particle accelerators
1. Cyclotron (Figure 24.7, page 903)
2. Linear Accelerator (Figure24.8, page 903)

1. 230Th + 1H --> 223Fr + 2 4He
3. Neutron Bombardment (Use fast neutrons to prepare isotopes)
1. 58Fe + 1n -> 59Fe
2. 59Fe -> 59Co + -1e
3. 59Co + 1n -> 60Co (Used for radiation treatment of cancer)