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Henri Becquerel
discovered radioactivity
Polonium and Radium
were discovered by Pierre and Marie Curie
Radioactivity
the spontaneous breaking up of unstable nuclei with the emission of one or more types of radiation
Alpha Particles
are groups of two protons and two neutrons, i.e. helium nuclei
Beta Particles
are fast-moving electrons
Gamma Rays
are high-energy electromagnetic radiation
Americium-241
a radioactive element that emits alpha particles, and is commonly used in smoke detectors
Geiger-Muller Tube
used to detect radioactive radiation
Alpha Particles
are stopped by a sheet of paper
Beta Particles
can penetrate about 5mm of aluminium
Gamma Rays
are only stopped by a thick block of lead
Nuclear Reaction
a process that alters the composition, structure or energy of an atomic nucleus
Chemical Reaction
involves electrons rather than the nucleus
no new element formed
no release of nuclear radiation
chemical bonds broken and formed
Nuclear Reaction
changes take place in nucleus and electrons not involved
a new element is formed
nuclear radiation is released
no chemical bond breaking or bond formation involved
Half Life
the time taken for half of the nuclei in any given sample to decay
Radioisotope
a radioactive isotope
Uses of Radioisotopes
medicine
archaeology
agricultural research
food irradiation
smoke alarms
in industry
Radiocarbon Dating
a technique used to determine the age of an object containing carbon
it is based on the ratio of carbon-14 to carbon-12 in the object
