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  • Radioactivity

  • RadioactivityThe process by which nuclei emit particles and raysThese penetrating particles and rays are called radiation.

  • Types of RadiationAlpha particle-two p+ and two n0 (helium nucleus)Changes identity of the atom (drops by two atomic #s)Little penetrating power (stopped by paper or skin)

  • Types of RadiationBeta particle- a high speed e-Comes from a neutron that breaks apartChanges identity of the atom (up one atomic #)Stopped by Al foil or woodSymbol is -1e or -1

  • Types of RadiationGamma RadiationHigh-energy photon emitted as a gamma rayOften emitted along with or radiationDoes not change identity of the isotopeHighly penetrating and very dangerous to humans

  • Radioactive Decay as EquationsThe symbols for the various particles are shown:

    When a radioisotope changes identity, this is called a transmutation reaction.

  • Half-LifeEvery radioisotope has its own rate of decay measured by its half-life.Half-life (t) is the time required for half the nuclei of that radioisotope to decayCould be a fraction of a second or billions of years.

  • FissionWhen nuclei of some isotopes are hit with neutrons, they split into smaller fragments. This is fission.Every time an isotope splits, TREMENDOUS amounts of energy are released.

  • Fission Chain ReactionIn a chain reaction, the neutrons produced strike other atoms, which produce more neutrons, etc.This is how a nuclear bomb works.It is also how reactors work, but with controls.

  • Nuclear ReactorsMake use of the energy produced by fission.

  • Nuclear ReactorsThe fuel rods from reactors, when spent, are a major waste issue.They are stored indefinitely, or shipped to another location.They wont be safe until the isotopes are stable, which depends on the half-life of the isotope.The next slide has some fuel rod photos.

  • Fuel Rods

  • FusionOccurs when nuclei combine to produce a heavier nucleus.Occurs naturally in the sun. (4 H nuclei become 1 He nucleus)It is how current nuclear warheads work.


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