In this lesson we will learn how unstable isotopes can undergo different types of nuclear decay.
By the end of this lesson you will be able to:
- Describe alpha, beta and gamma decay.
- Predict the products of different types of nuclear decay.
- Define half life and calculate how much of a radioactive substance will remain after a given amount of time.
- Compare the penetrating power of alpha, beta and gamma radiation.
- Define radiation dose and give examples of natural and artificial sources of radiation.
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- Some atoms are unstable due to unbalanced forces between nuclear particles – protons and neutrons.
- These isotopes, known as radioisotopes, undergo spontaneous nuclear decay.
- Nuclear decay involves the emission of nuclear radiation from the nuclei of radioisotopes.
- There are three main types of nuclear decay – alpha, beta and gamma.
- Alpha decay is the ejection of alpha particles (helium nuclei) from atoms.
- It decreases the atomic number and therefore results in the formation of a new element (transmutation). The mass number also decreases.
- Beta decay is the ejection of beta particles (electrons) from atoms.
- These electrons form when a neutron is converted into a proton and an electron.
- Beta decay increases the atomic number and therefore results in the formation of a new element. The mass number remains the same.
- Gamma decay is the emission of gamma rays (electromagnetic waves) from atoms.
- It does not change the atomic number (or mass number), therefore the type of element stays the same.
- The half life of a radioisotope is the time it takes for half of its nuclei to undergo nuclear decay.
- All types of radiation are damaging to living things, but each penetrates materials to different extents.
- Gamma radiation is the most penetrating and alpha radiation is the least penetrating.
- Radiation dose is a measure of how much radiation is absorbed by a substance or individual.
- Sources of radiation can be natural or artificial, with natural sources accounting for the majority of radiation absorbed by humans.
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