What Does it Mean to be Radioactive?
A substance that is radioactive has a nucleus that is unstable. In this usage, unstable means that the nucleus will spontaneously decay, or break down by releasing some of its particles and energy. Nuclei may lose only neutrons, or a combination of protons and neutrons. When a particle consisting of two protons and two neutrons are emitted at once, an alpha particle is said to have been released. Other particles can be released when the nucleus spontaneously undergoes radioactive decay.
Types of Radiation
Principally, there are three types of radiation emitted during radioactive decay. Alpha and beta radiation are both particles. Gamma radiation is energy, and is in fact a type of electromagnetic radiation. The aforementioned alpha particle is made of two protons and two neutrons, for a mass number of four. Due to its two protons, it is often referred to as a helium nucleus. Beta particles are electrons formed from the transformation of a neutron into a proton (within the nucleus) coupled with the emission of a small portion of negatively charged mass, hence an electron. Gamma rays have no mass or charge, and since they are electromagnetic radiation, they travel at the speed of light.  These types of radiation are summed up below:
  alpha beta gamma
Symbol
Speed 10% of the speed of light 90% of the speed of light at the speed of light
Penetrating Ability Low Moderate Excellent
Ionizing Power Excellent Fair Poor
Nuclear Weapons - Video Clips
These videos are in the public domain, so you are free to download and view them.

A is for Atom − Clearly produced by a pro-nuclear energy contingent, this video does give a great visual introduction to nuclear fission and the radioactivity of the elements.

Duck and Cover − 1951 video from the Federal Civil Defense Administration.  Cold War filmmaking at its best.

Daisy Girl Ad − Controversial 1964 campaign ad for incumbent President Lyndon Johnson.  It was only aired once and it has been interpreted by some that the ad implied challenger Barry Goldwater would lead the United States into a nuclear war.

Tale of Two Cities − Made in 1946, the commentary in this video shows an anti-Japanese bias.  However, the images of the destruction in Hiroshima and Nagasaki (note the factory windows and "shadows" in particular) provide viewers with visual evidence of the only nuclear attacks in human history.
Applications of Radioisotopes - Websites
All of these links open up the websites listed in a new window.

Nuclear Weapons:

  1. The Nuclear Weapons Archive ‒ a primer for any discussion on the chemistry and global nature of nuclear weapons.  Stay with the scientific material, but you may want to check out some of the pictures on the site.  They are at times awesome and at others horrific, but will be sure to stimulate your emotions in one way or another.
  2. The Radiation Effects Research Foundation is dedicated to studying the effects if radiation on survivors of the Hiroshima and Nagasaki bombings.
  3. The Effects of Nuclear Weapons ‒ an online edition of a book prepared by the United States Department of Defense and the Energy Research and Development Administration.
  4. Photographs of Hiroshima and Nagasaki ‒ be forewarned, some of them are disturbing.  Brought to you by the Japan Congress Against A- and H-Bombs.

Three Mile Island ‒ Fact sheet prepared by the Nuclear Regulatory Council on the Three Mile Island incident of 1979.

Chernobyl:

  1. A Washington Post story from 2002 on the status of Chernobyl's power plant
  2. This page provides a synopsis of the event and further links on the incident.

Nuclear Energy:

  1. An Energy Information Administration page that will get you started on American nuclear energy statistics.
  2. Information sheet from the EIA about New Jersey's nuclear energy usage.
  3. The United States Nuclear Regulatory Commission's Electronic Reading Room
  4. Marvin L. Adams of Texas A&M wrote this article hosted by the National Academy of Engineering.  It considers many factors (e.g. time, land space) and provides a succinct comparison of various energy sources.
  5. Uranium maps from the World Information Service on Energy's Uranium Project.

Nuclear Medicine:

  1. What is a PET scan?  This may be a little heavy for some, but it's worth it to check it out.
  2. More on radioisotopes in medicine.
Further Reading
(1) Ackerman, Sandra J. A Different Kind of CSI: Crime and Stable Isotopes. American Scientist. 2013, 101, 27-28.
(2) Alazraki, Naomi P. and Mishkin, Fred S.  Fundamentals of Nuclear Medicine, The Society of Nuclear Medicine: New York, 1984.
(3) Asimov, Isaac.  Understanding Physics, Volume III; Dorset Press: New York, 1988.
(4) Benrey, Ronald M.  Nuclear Experiments You Can Do...from Edison; Thomas Alva Edison Foundation: Southfield, MI, 1982.
(5) Cohen, Bernard L.  The Heart of the Atom; Anchor Books: Garden City, NY, 1967.
(6) Craven, C.J.  Our Atomic World; United States Atomic Energy Commission: Oak Ridge, TN, 1963.
(7) Dean, Joseph L.  Atomic Power; Nelson Doubleday Paperback: Garden City, NY, 1967.
(8) Grimes, Robin W. and Nuttall, William J. Science. 2010, 329, 799-803.
(9) Hyde, Earl K.  Synthetic Transuranium Elements; United States Atomic Energy Commission: Oak Ridge, TN, 1964.
(10) Kaplan, Irving.  Nuclear Physics, 2nd ed.; Addison-Wesley: Reading, MA, 1964.
(11) Lindenfeld, Peter.  Radioactive Radiations and Their Biological Effects; American Association of Physics Teachers: College Park, MD, 1985.
(12) Long, Michael E.  Half-Life: The Lethal Legacy of America's Nuclear Waste.  National Geographic, July 2002, pp 2-33.
(13) Miner, William N.  Plutonium; United States Atomic Energy Commission: Oak Ridge, TN, 1968.
(14) Reed, Cameron. From Treasury Vault to the Manhattan Project. American Scientist. 2011, 99, 40-47.
(15) Romer, Alfred.  The Restless Atom; Anchor Books: Garden City, NY, 1960.
(16) Wald, Matthew L.  What Now for Nuclear Waste?  Scientific American, August 2009, pp 46-53.