7 Radioactivity and Particles (Single Award)

1234567891011121314151617181920212223242526272829
Across
  1. 1. Atoms that gained electrons and so have a resultant negative charge.
  2. 3. A material that reacts to ionising radiation, allowing an image to be formed.
  3. 7. A barrier used to prevent radioactive daughter products leaving a nuclear reactor.
  4. 9. The process of neutrons released by a fission reaction, being absorbed by another unstable, large nuclei, and inducing further fission.
  5. 10. Atoms that have lost electrons and so have a resultant positive charge.
  6. 16. A positively charged particle consisting of two protons and two neutrons. They are highly ionising, but can be stopped by a few centimetres of air.
  7. 17. A negatively charged constituent of the atom, that are found in different energy levels, around the nucleus.
  8. 21. A high speed electron that a nucleus emits when a neutron converts into a proton. They are ionising but can be stopped by a thin sheet of aluminium.
  9. 22. The radioactive isotope used in nuclear reactors. It is often referred to as U-235.
  10. 23. Atoms with the same number of protons but different numbers of neutrons. The atomic number is the same, but the mass number is different.
  11. 26. Radiation that can cause cell mutations, damage cells and tissues, and lead to cancers.
  12. 28. The random process involving unstable nuclei emitting radiation to become more stable.
  13. 29. The number of protons found in an atom of a specific element. Each element has a different atomic number.
Down
  1. 2. The process of an object being exposed to nuclear radiation. The object doesn’t become radioactive.
  2. 4. Atoms with a resultant charge due to the loss or gain of electrons.
  3. 5. All matter has an associated energy. This means that mass can be converted into energy in the form of radiation.
  4. 6. The unwanted presence of radioactive atoms on other materials. It is hazardous due to the decay of the contaminating atoms.
  5. 8. The rate at which an unstable nucleus decays.
  6. 11. A medical imaging device that uses radioactive tracers and detectors to form internal body images.
  7. 12. The stable states in which electrons are found in around a nucleus. Electrons can transition to a higher energy level through the absorption of electromagnetic radiation and can transition to a lower energy level through the emission of electromagnetic radiation.
  8. 13. The time it takes for the number of unstable nuclei of an isotope in a sample to halve, or the time it takes for the initial count rate of a sample of the isotope to halve. It is different for different isotopes.
  9. 14. The joining of two small, light nuclei to form a larger, heavier one and release energy. It cannot happen at low pressures and temperatures since in these conditions the electrostatic repulsion of protons in the nucleus cannot be overcome.
  10. 15. The number of protons and neutrons in an atom.
  11. 18. A neutrally charged constituent of the nucleus.
  12. 19. Electromagnetic radiation emitted from a nucleus. They have a very high penetrating power and require several centimetre of lead to absorb them.
  13. 20. Products: Fission produces two smaller nuclei, two or three neutrons and gamma rays. These products are released with kinetic energy.
  14. 24. A positively charged constituent of the nucleus.
  15. 25. Radiation that is found in small quantities all around us and originates from natural sources such as rocks and cosmic rays, as well as from man-made sources such as nuclear weapons testing and accidents.
  16. 27. The splitting of a large and unstable nucleus into two smaller and more stable nuclei to produce energy. This is the method currently used in nuclear power stations.