Chapter 23 Lecture Outline

Nuclear Chemistry

1. Nuclear Particles

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

2. Radioactivity and reactions
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)

3. 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.

4. Production of New Nuclei
1. Particle accelerators
1. Cyclotron (Figure 24.7, page 903)
2. Linear Accelerator (Figure24.8, page 903)
2. Induced Radioactivity (Making a radioactive isotope)
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)
5. Half life of radioactive isotopes
1. Radioactive decay is first order
2. First order rate law

1. For half life t_1/2 = 0.693/k
2. Amount remaining after time t
6. Uses of Radioactivity (See Mathcad)
1. ²³⁸U Dating (Age of Rock Problem from Page 907)
1. ²³⁸U -> ²⁰⁶Pb t_1/2 = 4.5*10⁹ years
2. ⁴⁰K Dating
1. ⁴⁰K + _-1e -> ⁴⁰Ar t_1/2 = 1.3x10⁹ years
3. ¹⁴C Dating
1. ¹⁴N + ¹n -> ¹⁴C + ¹H
2. ¹⁴C -> _-1e + ¹⁴N t_1/2 = 5730 years
3. Shroud of Turin (Dated at 1300 AD). Determine ¹⁴C present. What would it be if 0 AD?
4. Radioactive Tracers and Labels
1. P-32 Biochemical Systems

C&EN Paper on Heavy-Ion Research

1. Discovery of New Elements, using traditional accelerators
1. ⁹⁶Mo + ²H -> ⁹⁷Tc + ¹n
2. ²³⁰Th + ¹H -> ²²³Fr + 2 ⁴He
3. ²⁰⁹Bi + ⁴He -> ²¹⁰At + 3 ¹n
2. Review Elements Created at GSI Institute

REACTION	DATE
54Cr + 209Bi -> 262107 + n	2/81
58Fe + 208Pb -> 265108 + n	3/84
58Fe + 209Bi -> 266109 + n	9/82
62Ni + 208Pb -> 269110 + n	11/94
64Ni + 209Bi -> 272111 + n	12/94

3. Elements 101 to 106
1. When 1955 to 1974 at LLL and Dubna
2. How Heavy element + light element (at high energy)
4. Elements 107 to 111
1. When 1980 to present
2. How Two Medium size elements at lower energy
3. Is this the same thing as "cold fusion" in the late 80's?
5. For a typical experiment discussed:
1. How many atoms of 111 were produced?
2. How long did it take to do?
3. How many moles is this?
4. How much would all the 111 ever produced weigh?
5. What is the half life for ²⁷²111? What is the rate constant?
6. Why does the cross section effect how difficult the experiment is?
7. Probability of a collision (1 mm² in 1 km²)
6. Beam Energy
1. Enough to overcome coulomb barrier
2. Not to much to cause fission
7. How the experiment works
1. Diagram of accelerator
2. Make ions from a source metal (ie ⁶⁴Ni⁹⁺ ions)
3. Accelerate 1 species in heavy ion accelerator
4. Second species is on rotating target (²⁰⁹Bi)
5. Detection: Products are heavy, separate from primary beam by EB Sectors
8. Why are they interested in 114
9. From Your Textbook, Section 24.6
1. Mass Defect for alpha partical ⁴He see Mathcad (pdf)
2. Fission
²³⁵U + ¹n -> ¹³⁹Ba + ⁹⁴Kr + 3 ¹n
3. Fusion
²H + ³H -> ⁴He + ¹n
4. Calculating energy from Fusion
1. Starting mass 2.0140 + 3.01605
2. Final mass 4.0026031 + 1.008665012
3. mass defect 0.018781 amu
4. energy per mole reaction?

Please send any comments, corrections, or suggestions to svanbram@science.widener.edu.

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