Chapter 19 Lecture Outline
Diagnosing Appendicitis
Types of Radioactivity
- Nuclear Particles
Name | Symbol | Symbol | Mass | Charge |
Alpha | [alpha] | ^{4}He | 4 | +2 |
Beta | [beta] | _{1-}e | 0 | -1 |
Gamma | [gamma] | | 0 | 0, radiation (light) |
Neutron | n | | 1 | 0 |
Proton | p | ^{1}H | 1 | +1 |
Positron | _{+1}e | _{+}[beta] | 0 | +1 |
- Radioactivity and
reactions
- Alpha emission: ^{238}U -> ^{234}Th + ^{4}He
- Beta Emission:
- ^{14}C -> ^{14}N + _{-1}e
- ^{1}n -> ^{1}p + _{-1}e (neutron -> proton + electron)
- Positron Emission
- ^{11}C -> ^{11}B + _{+1}e
- ^{1}p -> ^{1}n + _{+1}e (proton -> neutron + positron)
- Electron Capture
- ^{40}K + _{-1}e -> ^{40}Ar
- ^{1}p + _{-1}e -> ^{1}n (proton + electron -> neutron)
The Valley of Stability: Predicting the Type of Radioactivity
Nuclear Stability. Likelihood that isotope is radioactive depends upon:
- >83 protons are unstable
- Magic Numbers 2, 8, 20, 28, 50, 82 are stable. If magic number of both protons and
neutrons, then "double magic"
- Even numbers of neutrons or protons are stable.
- Both even, most stable
- One even one odd, less stable
- both odd, least stable
- Belt of stability
- If above, then decay to convert a neutron to a proton.
- If below, then positron emission (or electron capture) to convert a proton to a
neutron.
The Kinetics of Radioactive Decay and Radiometric Dating
- Half life of radioactive isotopes
- Radioactive decay is first order
- First order rate law
- For half life t_{1/2} = 0.693/k
- Amount remaining after time t
- Uses of Radioactivity (See Mathcad)
- ^{238}U Dating (Age of Rock Problem from Page 907)
- ^{238}U -> ^{206}Pb t_{1/2} = 4.5*10^{9} years
- ^{40}K Dating
- ^{40}K + _{-1}e -> ^{40}Ar t_{1/2} = 1.3x10^{9} years
- ^{14}C Dating
- ^{14}N + ^{1}n -> ^{14}C + ^{1}H
- ^{14}C -> _{-1}e + ^{14}N t_{1/2} = 5730 years
- Shroud of Turin (Dated at 1300 AD). Determine ^{14}C present. What would it be if 0 AD?
The Discovery of Fission: The Atomic Bomb and Nuclear Power
Converting Mass to Energy: Mass Defect and Nuclear Binding Energy
Nuclear Fusion: The Power of the Sun
The Effects of Radiation on Life
Radioactivity In Medicine
Production of New Nuclei
- Particle accelerators
- Cyclotron (Figure 24.7, page 903)
- Linear Accelerator (Figure24.8, page 903)
- Induced Radioactivity (Making a radioactive isotope)
- ^{230}Th + ^{1}H --> ^{223}Fr + 2 ^{4}He
- Neutron Bombardment (Use fast neutrons to prepare isotopes)
- ^{58}Fe + ^{1}n -> ^{59}Fe
- ^{59}Fe -> ^{59}Co + _{-1}e
- ^{59}Co + ^{1}n -> ^{60}Co (Used for radiation treatment of cancer)
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