Nuclear Energy, Fusion

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Nuclear Energy, Fusion Fission

• GPS SC1 Students will analyze the nature of
  matter and its classifications.
• a. Relate the role of nuclear fusion in producing
  essentially all elements heavier than helium.

• Essential Questions
• What are the four main radioactive decay
  emissions
• How is half life related to radioactivity?
• What comes to mind when you hear the term
  radioactive?

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Objectives

1. To learn the types of radioactive decay
2. To learn to write nuclear equations for
   radioactive decay
3. To learn how one element may be changed to
   another by particle bombardment
4. To learn about radiation detection instruments
5. To understand half-life

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A Review of Atomic Terms

• nucleons particles found in the nucleus of an
  atom
• neutrons
• protons
• atomic number (Z) number of protons in the
  nucleus
• mass number (A) sum of the number of protons
  and neutrons
• isotopes atoms with identical atomic numbers
  but different mass numbers
• nuclide each unique atom

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Nuclear Symbols
Element symbol
Mass number (p no)
Atomic number (number of p)
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A. Radioactive Decay

• radioactive nucleus which spontaneously
  decomposes forming a different nucleus and
  producing one or more particles
• nuclear equation shows the radioactive
  decomposition of an element

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NuclearStability
Decay will occur in such a way as to return a
nucleus to the band (line) of stability.
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A. Radioactive Decay
Types of Radioactive Decay

• 1. Alpha-particle production
• Alpha particle helium nucleus
• Examples

• Net effect is loss of 4 in mass number and loss
  of 2 in atomic number.

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Alpha Radiation
Alpha decay is limited to VERY large, nuclei such
as those in heavy metals.
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A. Radioactive Decay
Types of Radioactive Decay

• 2. Beta-particle production

• Beta particle electron
• Examples

• Net effect is to change a neutron to a proton.

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Beta Radiation
Beta decay converts a neutron into a proton.
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A. Radioactive Decay
Types of Radioactive Decay

• 3. Gamma ray release

• Gamma ray high energy photon
• Examples

• Net effect is no change in mass number or atomic
  number.

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Alpha Particle Emission Beta Particle Emission Gamma Ray Emission
Symbol or or
Mass Heavy Light No Mass
How it changes the nucleus Decreases the mass number by 4 Decreases the atomic number by 2 Converts a neutron into a proton Increases atomic number by 1 No change to the nucleus
Penetration Low Medium High
Protection provided by Skin Paper, clothing Lead
Danger Low Medium High
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A. Radioactive Decay
Types of Radioactive Decay

• 4. Positron production

• Positron particle with same mass as an electron
  but with a positive charge
• Examples

• Net effect is to change a proton to a neutron.

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A. Radioactive Decay
Types of Radioactive Decay

• 5. Electron capture

• Example

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A. Radioactive Decay
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A. Radioactive Decay
Decay series
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B. Nuclear Transformations

• Nuclear transformation change of one element to
  another
• Bombard elements with particles

Examples
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B. Nuclear Transformations

• Transuranium elements elements with atomic
  numbers greater than 92 which have been
  synthesized

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C. Detection of Radioactivity and the Concept of
Half- life

• Geiger-Muller counter instrument which measures
  radioactive decay by registering the ions and
  electrons produced as a radioactive particle
  passes through a gas-filled chamber

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C. Detection of Radioactivity and the Concept of
Half- life

• Scintillation counter instrument which measures
  the rate of radioactive decay by sensing flashes
  of light that the radiation produces in the
  detector

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C. Detection of Radioactivity and the Concept of
Half- life

• Half-life time required for half of the
  original sample of radioactive nuclides to decay

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Objectives

1. To learn how objects can be dated by
   radioactivity
2. To understand the use of radiotracers in medicine

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A. Dating by Radioactivity
Radiocarbon dating

• Originated in 1940s by Willard Libby
• Based on the radioactivity of carbon-14

• Used to date wood and artifacts

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B. Medical Applications of Radioactivity
Radiotracers

• Radioactive nuclides that can be introduced into
  organisms and traced for diagnostic purposes.

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Objectives

1. To introduce fusion and fission as sources of
   energy
2. To learn about nuclear fission
3. To understand how a nuclear reactor works
4. To learn about nuclear fusion
5. To see how radiation damages human tissue

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A. Nuclear Energy

• Two types of nuclear processes can produce energy
  
• Combining 2 light nuclei to form a heavier
  nucleus - fusion
• Splitting a heavy nucleus into 2 nuclei with
  smaller mass numbers - fission

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B. Nuclear Fission

• Releases 2.1 ?1013 J/mol uranium-235
• Each fission produces 3 neutrons

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B. Nuclear Fission

• Chain reaction self sustaining fission process
  caused by the production of neutrons that proceed
  to split other nuclei
• Critical mass mass of fissionable material
  required to produce a chain reaction

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B. Nuclear Fission
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C. Nuclear Reactors
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C. Nuclear Reactors
Reactor core
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D. Nuclear Fusion

• Process of combining 2 light nuclei
• Produces more energy per mole than fusion
• Powers the stars and sun

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D. Nuclear Fusion

• Requires extremely high temperatures

• Currently not technically possible for us to use
  as an energy source

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Energy and Mass

• Nuclear changes occur with small but measurable
  losses of mass. The lost mass is called the mass
  defect, and is converted to energy according to
  Einsteins equation
• DE Dmc2
• Dm mass defect
• DE change in energy
• c speed of light

Because c2 is so large, even small amounts of
mass are converted to enormous amount of energy.
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E. Effects of Radiation
Factors Determining Biological Effects of
Radiation

• Energy of the radiation
• Penetrating ability of the radiation
• Ionizing ability of the radiation

• Chemical properties of the radiation source

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E. Effects of Radiation
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E. Effects of Radiation