Chapter 21: Nuclear Chemistry

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Chapter 21 Nuclear Chemistry
Chemistry 1062 Principles of Chemistry II Andy
Aspaas, Instructor
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Nuclear chemistry

• Chemical reactions where the nuclei change
• Independent of chemical surroundings (i.e. it
  doesnt matter what compounds the nuclei are part
  of)
• Radioactive decay unstable nuclei spontaneously
  disintegrate and give off radiation
• Nuclear bombardment reactions one nucleus is
  physically struck by another nucleus to cause a
  nuclear reaction

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Nuclear equations

• Nuclei only!
• Nuclide symbols used to show
• Mass number, A
• Atomic number, Z
• For particles with no protons, the atomic number
  represents the charge
• Ex. electron
• Total mass numbers and atomic numbers must be
  equal on both sides of reaction

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Radioactivity

• Alpha emission ejection of a helium-4 nucleus
• Occurs in nuclei where Z gt 83 (transuranium)
• Ex.
• Beta emission ejection of a high-speed electron
• Occurs when N/Z is too large (N neutrons)
• Ex.

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Radioactivity

• Positron emission ejection of a positron
• Positron positively charged particle with same
  mass as an electron
• Occurs when N/Z is too small
• Ex.
• Electron capture adding an electron to the
  nucleus
• Competes with positron emission when N/Z is too
  small
• Ex.

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Radiation

• Gamma emission emission of a gamma photon from
  an excited state nucleus
• Metastable nucleus excited nucleus a lifetime of
  at least one nanosecond
• Ex.
• Spontaneous fission when a nucleus Z gt 89
  spontaneously breaks apart into other nuclei
• Ex.

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Predict the decay

• Predict the form of radioactive decay the
  following nuclei will have, and if possible,
  write a nuclear equation

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Nuclear bombardment reactions

• Nuclei such as uranium-235 can be caused to split
  into several other nuclei if bombarded by a
  neutron
• Fission produces more neutrons, which can go on
  to cause other uranium nuclei to split
• The result is a chain reaction which releases the
  energy of neutron bombs and nuclear fission
  reactors

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Nuclear fission reactor

• Pressurized light water reactor
• Most commondesign in US
• Prairie Island, MN

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Prairie Island Nuclear Generating Plant, Red
Wing, MN