Nuclear radiation and radioactive decay: Radioactivity: Physics: GCSE (9:1)

• The half-life is the time taken for one half of the radioactive atoms to decay.
• count-rate


  the number of decays recorded each second by a detector

  
• becquerels (Bq)

  the SI unit for activity
• activity


  the rate at which a source of unstable nuclei decays
• Geiger-Muller (GM) tube

  A device that can detect ionising radiation and is used to measure the activity of a radioactive source

  
• Effect of gamma decay on atomic and mass numbers

  There is no change to the atomic or mass numbers

  
• Change to the nucleus due to gamma decay

  There is no change to the particles in the nucleus

  
• Effect of beta decay on atomic and mass numbers

  The atomic number increases by one and the mass number remains the same

  
• Change to the nucleus due to beta decay

  A neutron turns into a proton

  
• Effect of alpha decay on atomic and mass numbers

  The mass number decreases by four and the atomic number decreases by two

  
• Change to the nucleus due to alpha decay

  The nucleus loses two protons and two neutrons

  
• Gamma ray (γ)


  Electromagnetic radiation from the nucleus

  
• Beta particle (β)


  A high speed electronejected from the nucleus

  
• Alpha particle (α)


  Consists of two neutrons and two protons and is identical to a helium nucleus

  
• Types of nuclear radiation

  Alpha particle, beta particle, gamma ray, neutron
• Nuclear radiation

  Radiation emitted from an unstable nucleus during radioactive decay

  
• Radioactive decay

  A random process in which an unstable nucleus will emit one or more types of nuclear radiation to become more stable

  
• Unstable nuclei


  Nuclei with too few or too many neutrons
• Stable nuclei


  Nuclei that contain a certain amount of neutrons compared to protons
• Geiger counters are used to measure background radiation levels and to monitor radiation exposure during medical procedures such as CT scans.
• A Geiger counter consists of a detector tube filled with gas that emits electrons when exposed to radiation, creating a current flow through the circuit.
• Radioactivity can be measured using a Geiger counter, which detects ionising radiation by measuring the number of times it produces an electrical pulse.
• Geiger counters are used to detect alpha particles because they have high ionization power but low penetrating ability.
• Long term exposure to low levels of radiation is linked to increased cancer risk, especially leukemia and solid cancers.
• Exposure to ionizing radiation can cause genetic mutations by damaging DNA.
• Alpha particles have two positive charges and four times the mass of a helium atom.
• Gamma rays are high-energy photons produced by the nucleus.
• Alpha particles cannot penetrate more than a sheet of paper due to their large mass and positive charge.
• Beta particles are negatively charged electrons ejected from the nucleus of some unstable atoms.