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7.1 Atoms & Radiation, 7.3 continued, 7.2 The Discovery of the Nucleus…
7.1 Atoms & Radiation
there are 3 main types of radiation: alpha, beta & gamma
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radioactive sources emit alpha, beta & gamma radiation
7.3 continued
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neutrons are emitted by some radioactive substances as a result of alpha particles colliding with unstable nuclei
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7.4 more about a, b & y radiation
a, b & y radiation are types of ionising radiation. this means they have enough energy to knock electrons off atoms forming ions
as they ionise atoms they lose energy and are stopped. the stronger their ionising ability the less they can penetrate a material
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ionising radiation is dangerous as it can kill or mutate cells in the body. mutated cells can cause cancers
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7.5 activity & half life
count rate is the number of counts per second recorded by a radioactivity detector such as a GM tube
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radioactive decay is a random process. but you can predict what proportion of nuclei will decay in a given time
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the half life is the time it takes for the count rate, activity or un-decayed nuclei in a sample to halve
7.7 Nuclear Fission
in a nuclear reactor, control rods absorb fission neutrons to ensure that only one neutron per fission goes onto produce another fission
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7.8 Nucleur Fusion
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during this process some of the mass of the smaller nuclei is converted into energy is the form of kinetic energy of the new nucleus and gamma rays. this produces a very large amount of energy
to get the smaller nuclei to fuse they must hit each other very hard to overcome the electrostatic repulsion of the protons. this means they must have a very high temperature and pressure
in nature this is found in the core of stars and during the collision of very large objects such as neutrons, stars and black holes