Nuclear Chemistry

1
Chapter 11

• Nuclear Chemistry

2
Review

• Chapter 3 Discussed atomic number and mass
  number of an element
• Nucleons another name used to describe the
  protons neutrons in a nucleus

3
Nuclear Reaction

• Nuclear Reaction - A reaction that changes an
  atomic nucleus, usually causing the change of one
  element into another.

4
Nuclear Reactions
5
Discovery of Radioactivity

• Radioactivity The spontaneous emission of
  radiation from a nucleus

6
Discovery of Radioactivity
7
Stable and Unstable Isotopes

• Radioisotope radioactive isotope of an element
• Every element has at least 1 radioisotope
• Every element has at least 1 isotope with an
  unstable nucleus (radionuclide)
• Radiation is emitted hen the radioisotope
  spontaneously changes from an atom with an
  unstable nucleus to an atom with a more stable
  nucleus

8
Stable and Unstable Isotopes

• Radioisotopes
• Artificial radioisotopes not found in nature
• All isotopes of elements heavier than uranium
• Natural radioisotopes radioisotopes that occur
  naturally
• Radioisotopes undergo the same reactions as
  stable isotopes of an element
• Because they can be located with a radiation
  detector they are good TRACERS

9
Nuclear Decay

• Nuclear decay The spontaneous emission of a
  particle from an unstable nucleus.
• Transmutation The change of one element into
  another.
• A balanced equation associated with radioactive
  decay involves balancing protons, nuclides,
  charges but not atoms

10
Nuclear Decay

• Alpha Emission
• Beta Emission
• Gamma Emission
• Positron Emission
• Electron Capture

11
Nuclear Decay

• Alpha Emission nucleus loses 2 protons and 2
  neutrons

12
Nuclear Decay

• Beta emission involves decomposition of a
  neutron to produce a proton and an electron

13
Nuclear Decay

• Positron emission involves the conversion of a
  proton in a nucleus to a neutron and a positron
• Positron has the same mass as an electron but a
  different charge

14
Nuclear Decay

• Electron capture (EC) - a process in which the
  nucleus captures an inner-shell electron from the
  surrounding electron cloud, thereby converting a
  proton into a neutron.

15
Nuclear Decay

• Gamma Emission although they can occur alone
  more often they occur in conjunction with alpha
  and beta emissions.
• As the alpha and beta emissions occur excess
  energy is given off in the form of gamma rays

16
Nuclear Decay
17
Radioactive Half-Life

• Half-life describes how long it takes for ½ of
  the sample to decay
• Each passage of a half-life causes ½ of whatever
  sample remains to decay

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Detecting Radiation

• Photographic Film Badge
• Geiger Counter
• Scintillation Counter

19
Measuring Radiation
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Measuring Radiation

• The biological consequences of different
  radiation doses are shown below.
• The average annual radiation dose is only about
  0.27 rem. About 80 of this background radiation
  comes from natural sources the remaining 20
  comes from medical procedures and from consumer
  products.

21
Artificial Transmutation

• Very few of the approximately 3300 known
  radioisotopes occur naturally. Most are made from
  stable isotopes by artificial transmutation, the
  change of one atom into another brought about by
  nuclear bombardment reactions.
• 14N 1n ? 14C 1H

22
Nuclear Fission and Nuclear Fusion

• Nuclear fission The fragmenting of heavy nuclei.
• Chain reaction A reaction that is
  self-sustaining.
• Vast amounts of heat are produced power plants

23
Nuclear Fission and Nuclear Fusion

• Nuclear fusion The joining together of light
  nuclei.
• Light nuclei such as the isotopes of hydrogen
  release enormous amounts of energy when they
  undergo fusion. It is fusion reactions of
  hydrogen nuclei to produce helium that powers our
  sun and other stars.
• The necessary conditions for nuclear fusion are
  not easily created on Earth.

24
Optional Homework

• Text 11.17, 11.18, 11.20, 11.30, 11.32, 11.36,
  11.40, 11.44, 11.46, 11.48, 11.50, 11.52, 11.54,
  11.56, 11.58
• Chapter 11 Homework on the website

25
Required Homework

• Chapter 11 Assignment