Radioactive DecayAQA GCSE Physics: Flashcards

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What is radioactive decay?

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What is radioactive decay?: A random process in which an unstable nucleus emits radiation to become more stable.
What is activity, and what unit is it measured in?: The rate at which a source decays, measured in becquerels (Bq); 1 Bq = 1 decay per second.
What is an alpha particle?: Two protons and two neutrons — the same as a helium nucleus.
What is a beta particle?: A high-speed electron ejected from the nucleus when a neutron turns into a proton.
What is a gamma ray?: Electromagnetic radiation emitted from the nucleus.
Rank alpha, beta and gamma radiation from most to least ionising.: Alpha (most ionising) > beta > gamma (least ionising).
Rank alpha, beta and gamma radiation from most to least penetrating.: Gamma (most penetrating) > beta > alpha (least penetrating, stopped by paper).
What happens to mass number and atomic number in alpha decay?: Mass number decreases by 4; atomic number decreases by 2.
What happens to mass number and atomic number in beta decay?: Mass number stays the same; atomic number increases by 1.
What happens to mass number and atomic number in gamma emission?: Neither changes — only energy is released.
What is contamination?: The unwanted presence of radioactive atoms on or in another material.
What is irradiation?: Exposing an object to nuclear radiation from a source, without the object becoming radioactive itself.
Name two natural sources of background radiation.: Rocks/soil (radon gas) and cosmic rays from space (also accept food/drink).
Name two man-made sources of background radiation.: Nuclear weapons fallout and medical procedures (also accept nuclear accidents).
Give one medical use of radioactive sources.: Using tracers to explore internal organs, or radiation to control/destroy unwanted tissue such as tumours.