Nuclear Chemistry

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Nuclear Chemistry
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Radioactive Decay

• a-decay
• b-decay
• g-decay

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Other Modes of Decay

• Positron emission
• PET Scans
• Neutron capture

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Nuclear Stability

• Stable
• Radioactive

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Radioactive Dating

• Carbon-14

t1/2 5730 years
7.5 kg produced per year throughout entire
atmosphere. 14C activity in living material is
15.3 disintegrations per minute per gram.
How much 14C remains in dead organic material?
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Carbon-14 Dating

• The linen wrappings of the Dead Sea Scrolls,
  found in 1947, have an activity of 12
  disintegrations per minute per gram (d min-1 g-1.
  Compute the age of the linen.

t1/2 5730 years
k 1.21 x 10-4 year-1
t 2.0 x 103 years
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Binding Energy

• Mass Defect - The mass of the nucleus is less
  than the sum of the masses of the individual
  nucleons
• The mass defect is converted to energy and
  released when nuclei are formed.
• The energy released is given by
• EDmc2
• (Youve seen it before, now you can use it!)

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Binding Energy
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Binding Energy - Sample Calculation for Helium
Mass Defect -
Convert to kg -
Compute Energy
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Curve of the Binding Energy
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Nuclear Fission

• Nucleus Splits into Smaller Nuclei
• Larger Binding Energy of Smaller Nuclei Results
  in the Release of Energy
• 235U - Natural Abundance 0.720
• 1 kg yields 9.0 x 1013 J - Equivalent to 33,000
  tons of TNT
• 239Pu - Created through neutron bombardment of
  238U

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Fission Energy - Sample Calculation - Page 1
235U n 138Xe 95Sr 3 n
We start by computing the mass defect (product
mass - reactant mass)
Now we convert to kg
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Fission Energy - Sample Calculation - Page 2
Energy Release E Dmc2
For each atom we have
Now we can compute the energy released per gram
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Uranium Fission
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Nuclear Chain Reaction
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Nuclear Energy