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Nuclear Fission

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Nuclear Fission Stability of elements is best around a mass number of 60. Atoms with a mass number greater than 60 tend to gain stability by fragmenting. – PowerPoint PPT presentation

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Title: Nuclear Fission


1
Section 24-3
Nuclear Fission
  • Stability of elements is best around a mass
    number of 60.
  • Atoms with a mass number greater than 60 tend to
    gain stability by fragmenting.
  • The splitting of nuclei into fragments is known
    as nuclear fission.
  • Fission is accompanied with a very large release
    of energy.

2
Section 24-3
Nuclear Fission
  • Nuclear power plants use fission to produce
    electricity by striking uranium-235 with neutrons.

3
Section 24-3
Nuclear Fission (cont.)
  • Each fission of U-235 releases three additional
    neutrons.
  • Each of those neutrons can release three more
    neutrons.
  • The self-sustaining process is called a chain
    reaction.
  • http//glencoe.mcgraw-hill.com/sites/007874637x/st
    udent_view0/chapter24/concepts_in_motion.html

4
Section 24-3
Nuclear Fission (cont.)
5
Section 24-3
Nuclear Fission (cont.)
  • There must be sufficient mass to get the chain
    reaction started. If not the neutrons escape
    before striking other nuclei.
  • Without sufficient mass, neutrons escape from the
    sample before starting a chain reaction.
  • Samples with enough mass to sustain a chain
    reaction are said to have critical mass.
  • Samples with mass that is much greater than the
    critical mass have a reaction that escalates at a
    violent level and can cause a nuclear explosion.
    This is the supercritical mass.

6
Section 24-3
Nuclear Fission (cont.)
http//www.youtube.com/watch?vqybUFnY7Y8w
7
Section 24-3
Nuclear Reactors
  • Nuclear fission produces the energy generated by
    nuclear reactors.
  • The fission within a reactor is started by a
    neutron-emitting source and is stopped by
    positioning the control rods to absorb virtually
    all of the neutrons produced in the reaction.

8
Section 24-3
Nuclear Reactors (cont.)
  • The reactor core contains a reflector that
    reflects neutrons back into the core, where they
    react with fuel rods.
  • Nuclear reactors produce highly radioactive
    nuclear waste.
  • Breeder reactors produce more fuel than they
    consume.

9
Section 24-3
Nuclear Reactors (cont.)
10
Section 24-3
Nuclear Fusion
  • It is possible to bind together two or more
    lighter elements (mass number less than 60).
  • The combining of atomic nuclei is called nuclear
    fusion.
  • Nuclear fusion is capable of releasing very large
    amounts of energy.
  • The sun is powered by the fusion of hydrogen
    atoms to form helium atoms and a lot of energy.

11
Section 24-3
Nuclear Fusion (cont.)
  • Fusion has several advantages over fission.
  • Lightweight isotopes are abundant.
  • Fusion products are not radioactive.
  • However, fusion requires extremely high energies
    to initiate and sustain a reaction.

12
Section 24-3
Nuclear Fusion (cont.)
  • Fusion reactions are also known as thermonuclear
    reactions.
  • Many problems must be solved before nuclear
    fusion is a practical energy source.

13
Section 24-3
Section 24.3 Assessment
Bombarding a nuclei with charged particle in
order to create new elements is called ____.
A. nuclear conversion B. nuclear decay
C. induced decay D. induced transmutation
  1. A
  2. B
  3. C
  4. D

14
Section 24-3
Section 24.3 Assessment
Thermonuclear reactions involve A. splitting
nuclei into smaller fragments B. fusing nuclei
together to form larger particles
C. bombarding nuclei with charged particles
D. generating electricity in a nuclear reactor
  1. A
  2. B
  3. C
  4. D
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