Atomic structure and radiation

• Isotope

  Atoms with the same proton number but different neutron number (different mass number)
• Nucleus

  The centre of the atom that contains protons and neutrons
• Alpha radiation

  Helium nucleus 2p 2n
• Beta radiation

  fast moving electrons from the nucleus
• Gamma radiation

  Electromagnetic wave
• Ionising


  when electrons are added or removed from the atom
• penetrating


  what is needed to absorb the radiation
• half-life

  time taken for activity, count rate, number of nuclei or mass of isotopes to half
• Fission


  the splitting of a large unstable nuclei into two smaller nuclei roughly equal in size, neutrons, energy and gamma
• Fusion

  the joining of nuclei, typically happens in stars
• contamination


  when the radioactive source is on or in something
• irradiation

  when atoms in an object become ionised
• sievert

  dose of radiation applied to living objects
• Radioactive decay

  The process of an unstable nuclei giving out radiation to become more stable
• Alpha decay

  mass number decreases by 4 atomic number decreases by 2
• beta decay

  a neutron decays into a proton and an electron, atomic number increases by 1 and the mass number stays the same
• ion

  an atom that has gained or lost 1 or more electrons
• alpha radiation has a:

  Range of a few cm in air, is very strongly ionising, stopped by paper and deflected in EM fields
• Beta radiation has a:

  Range of a few m in air, strongly ionising, stopped by a few mm of aluminium and is deflected in EM fields
• Gamma radiation has a

  Range of many km in air, weakly ionising, stopped by many mm of lead or a few m of concrete, is not deflected in EM fields
• Is decay random

  Yes. Radioactive decay is random and impossible to predict
• natural sources of background radiation are

  radon gas, rocks and buildings, cosmic rays and food/drink
• Artificial sources of background radiation are:

  Nuclear weapons testing and power stations as well as medical like x-ray
• Are isotopes with short half lives more dangerous than those with long ones?

  yes since they decay faster so emit more radiation per second