The time taken for the mass of a radioactive isotope to decrease half the initial mass or for its activity to halve.
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What is the activity of an isotope?
Is the number of nuclei of the isotope that disintegrates per second.
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How do you calculate the power of a source?
By the product of its activity and the energy of each particle.
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What is radioactivity?
The spontaneous emission of an alpha or beta particle from the nucleus of an atom, causing the proton number of the atom to change.
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What are the properties of an alpha particle?
It has 2 protons and 2 neutrons, 5cm in air- can be stopped by thick sheet paper and is highly ionising.
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What are the properties of a beta particle?
It has fast moving electrons, stop by a few millimetres of aluminium and is less ionising that alpha but more than gamma.
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What are the properties of gamma?
Very high frequency, reduced by several metres of concrete and its very weak in ionisation.
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What sort of atoms decay?
Atoms that are unstable.
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Why may atoms be unstable?
1) They are too large 2) The balance between proton and neutrons is not right.
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What is background radiation and what sources does it include?
It is radiation due to naturally occurring radioactive substances in the environment. some of them are as follow; 1)Rocks -such as granite 2) Radon Gas- formed in the ground 3) Cosmic Rays- come from space
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What is the equation that leads to an exponential decay curve?
A= λN, Where A stands for the activity, λ is the decay constant and N is the number of undecayed atoms.
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What is Carbon-14 suitable for?
1) Its presence in all living things 2) The length of its half life- sufficiently short so changes can be observed over thousands of years.
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Which type of radiation is used for sterilization?
Gamma rays, used to keep fresh food for longer and for medical instruments.
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What are the damages that radiation can cause?
1) radiation burns 2) hair loss 3) radiation sickness 4) damage to reproductive organs 5) delayed effects such as cancer and leukemia.
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Other cards in this set
Card 2
Front
What is the activity of an isotope?
Back
Is the number of nuclei of the isotope that disintegrates per second.
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