Radiation and the Environment Nuclear Changes
Fission vs. Fusion
Fission
Fission Nuclei of some elements can spontaneously lose particles or give off high energy radiation, split apart, or fuse together. Natural radioactive decay is a nuclear change in which unstable isotopes spontaneioudly emit fast-moving particles The left-overs are isotopes.
Fig. 2-6, p. 28 Stepped Art Neutron Uranium-235 Fission fragment Fission fragment Energy n n n n n n Uranium-235 Nuclear (Fission) Chain Reaction
Half Life Each Isotope decays at a specific rate characteristic of that isotope. When one half of the original sample is leftover, that time is the isotope’s half-life. The shorter the half-life the more radioactive the particle.
Fission Controlled chain reactions are what power our nuclear reactors. Uncontrolled chain reactions are what cause a nuclear explosion.
Nuclear Fusion While splitting an atom is called fission. Combining atoms is called fusion. It releases an enormous amount of energy. Only found in stars.