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.