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chemistry - Coggle Diagram
chemistry
Radioactive decay
An atom's nucleus can only be stable if it has a certain number of neutrons for the number of protons it has.
Elements with fewer protons, such as the ones near the top of the periodic table, are stable if they have the same number of neutrons and protons, for example carbon, carbon-12 is stable and has six protons and six neutrons.
as the number of protons increases, more neutrons are needed to keep the nucleus stable, for example lead, lead-206 has 82 protons and has 124 neutrons.
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Half-life
Half-life is the time it takes for half of the unstable nuclei in a sample to decay or for the activity of the sample to halve or for the count rate to halve.
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The half-life of cobalt-60 is 5 years. If there are 100 g of cobalt-60 in a sample, how much will be left after 15 years?
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Nuclear equations
A nucleus changes into a new element by emitting nuclear radiations; these changes are described using nuclear equations.
Example
Alpha decay (two nuclei and two neutrons) changes the mass number of the element by minus four and the atomic number by minus two. An alpha particle is the same as a helium-4 nucleus.
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