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Radioactivity

Radioactivity. Radioactivity. The process by which nuclei emit particles and rays These penetrating particles and rays are called radiation. 4. Symbol is 2 He or 2 α. 4. Types of Radiation. Alpha particle-two p + and two n 0 (helium nucleus)

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Radioactivity

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  1. Radioactivity

  2. Radioactivity • The process by which nuclei emit particles and rays • These penetrating particles and rays are called radiation.

  3. 4 • Symbol is 2He or 2α 4 Types of Radiation • Alpha 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)

  4. Types of Radiation • Beta particle- a high speed e- • Comes from a neutron that breaks apart • Changes identity of the atom (up one atomic #) • Stopped by Al foil or wood • Symbol is -1e or -1β

  5. Types of Radiation • Gamma Radiation • High-energy photon emitted as a gamma ray • Often emitted along with α or β radiation • Does not change identity of the isotope • Highly penetrating and very dangerous to humans

  6. Radioactive Decay as Equations • The symbols for the various particles are shown: • When a radioisotope changes identity, this is called a transmutation reaction.

  7. Half-Life • Every radioisotope has its own rate of decay measured by its half-life. • Half-life (t½) is the time required for half the nuclei of that radioisotope to decay • Could be a fraction of a second or billions of years.

  8. Fission • When 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.

  9. Fission Chain Reaction • In 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.

  10. Nuclear Reactors • Make use of the energy produced by fission.

  11. Nuclear Reactors • The fuel rods from reactors, when spent, are a major waste issue. • They are stored indefinitely, or shipped to another location. • They won’t be safe until the isotopes are stable, which depends on the half-life of the isotope. • The next slide has some fuel rod photos.

  12. Fuel Rods

  13. Fusion • Occurs 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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