Radiation and the Radiation and the EnvironmentEnvironment

Nuclear ChangesNuclear Changes

Fission vs. FusionFission vs. Fusion

FissionFission

FissionFission

Nuclei of some elements can spontaneously Nuclei of some elements can spontaneously lose particles or give off high energy lose particles or give off high energy radiation, split apart, or fuse together.radiation, split apart, or fuse together.

Natural radioactive decay is a nuclear Natural radioactive decay is a nuclear change in which unstable isotopes change in which unstable isotopes spontaneioudly emit fast-moving particles spontaneioudly emit fast-moving particles

The left-overs are isotopes.The left-overs are isotopes.

Fig. 2-6, p. 28Stepped Art

Neutron

Uranium-235

Fissionfragment

Fissionfragment

Energyn

n

n

Energy

Energy

n

n

n

Energy

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Nuclear Nuclear (Fission) (Fission)

Chain Chain ReactionReaction

Half LifeHalf Life

Each Isotope decays at a specific rate Each Isotope decays at a specific rate characteristic of that isotope. characteristic of that isotope.

When one half of the original sample is When one half of the original sample is leftover, that time is the isotope’s half-life.leftover, that time is the isotope’s half-life.

The shorter the half-life the more radioactive The shorter the half-life the more radioactive the particle. the particle.

FissionFission

Controlled chain reactions are what power Controlled chain reactions are what power our nuclear reactors.our nuclear reactors.

Uncontrolled chain reactions are what cause Uncontrolled chain reactions are what cause a nuclear explosion. a nuclear explosion.

Nuclear FusionNuclear Fusion

While splitting an atom is called fission. Combining While splitting an atom is called fission. Combining atoms is called fusion. atoms is called fusion.

It releases an enormous amount of energy. It releases an enormous amount of energy. Only found in stars.Only found in stars.