definitions 7.1

Radioactivity
The release of high-energy particles and rays of energy from a substance as a result of changes in the nuclei of its atoms.
natural background radiation
The stream of high-energy, fast-moving particles or waves that is found in our environment.
Radiation
High-energy rays and particles emitted by radioactive sources.
light
One form of radiation that is visible to humans.
Isotopes
Different atoms of a particular element that have the same number of protons but different numbers of neutrons.
Mass number =
protons + neutrons
Radioactive Decay
The process in which unstable nuclei lose energy by emitting radiation.
Alpha Particles


 

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a Helium atom

Beta Particles

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an electron

Gamma radiation

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rays of high-energy

Alpha Decay
The emission of an alpha particle from a nucleus.
Beta Decay
A neutron changes into a proton and an electron. The proton remains in the nucleus, the electron shoots out from the nucleus.
Gamma Decay
A redistribution of energy within the nucleus. A high-energy gamma ray is given off as the isotope falls from a high-energy state to a lower energy state.