Radioactivity

Radioactivity- the spontaneous emission of radiation by an unstable atomic nucleus

Discovered by Henri Becquerel and the Curies

Atomic mass

SymbolAtomic number

Cannot see, hear, smell, taste or touch it.

Geiger counter Film badges Scintillation counter

Alpha, α Beta, β

Gamma, γ Decay- the release of

radiation by radioactive isotopes

Alpha particles Helium nucleus, 2 protons and 2 neutrons 4

2 He 2+

α Are large in size, move slowly Easily stopped by paper or clothing When an alpha particle is emitted from

Uranium, it decays to Thorium

High energy electron

0-1 e

β -

Neutron from the nucleus changes into a proton and an electron and the electron is emitted

Are smaller than alpha particles and move faster

Can be stopped by sheets of metal, wood, bricks

γ High energy form of electromagnetic

radiation No mass or charge Can pass through most materials Can be stopped by lead or thick concrete Usually accompanied by other forms of

radiation Most harmful form of radiation

Fission- a nuclear reaction in which a nucleus is broken into two or more smaller nuclei, creates a more stable nucleus

Chain reaction- a self-propagating reaction in which uranium absorbs a neutron by bombardment, the nucleus becomes unstable and splits, emitting neutrons and energy

Critical mass- the minimum amount of material needed to sustain a nuclear reaction

Fusion- the process where small nuclei join to form larger nuclei, creates a more stable nucleus

Energy produced from the fusion of 1 kilogram of Hydrogen into Helium to the fission of 1 kilogram of Uranium is 20:1

Moderators- used to slow down the speed at which the neutrons collide, can be water, beryllium or graphite

Control rods- rods/ plates that are lowered into the fuel rod assembly to absorb some of the neutrons, controls the rate of reaction

Carbon dating Medical diagnosis and treatment Tracers Preserving food