Rayneritis!

1. Rayneritis! Fill in the summary sheet on Nuclear radiation

2. Alpha, beta and gamma radiation An alpha particle consists of two protons and two neutrons. It is strongly ionising. A beta particle is a high speed electron. It is produced when a neutron has decays into an electron and proton. It is moderately ionising. Gamma rays are very high frequency electromagnetic waves. They are produced when an unstable nucleus loses energy.. They are weakly ionising.

3. The penetrating power of alpha, beta and gamma radiation Paper or a few cm of air stops alpha particles 1cm or 1m of air of aluminium stops beta particles Several cm of lead or 1m of concrete is needed to stop gamma rays

4. Learning today • The dangers of nuclear radiation • What background radiation is • How to detect radiation using • Photographic film • Geiger-Muller tube • Cloud chamber – alpha particles

5. Choose appropriate words to fill in the gaps below: Atoms consist of a very small _______, containing protons and neutrons, surrounded by _______. Atoms of the same element will always have the same number of _______ but different ________ of the same element will have different numbers of _________. The atoms of some substances are unstable and _________. They may give off alpha or ______ particles or gamma rays. Gamma rays are the most penetrating type of radiation, _____ is the least. nucleus electrons protons isotopes neutrons radioactive beta alpha WORD SELECTION: alpha protons electrons isotopes beta nucleus neutrons radioactive

6. Safety • Keep your Distance • Use tongs • Use a lead apron or screen • Work with mechanical robot arms Fill in the note sheet

7. Dangers of radioactivity Alpha Beta Gamma Radiation will ionise atoms in living cells – this can damage them and cause cancer or leukaemia. OUTSIDE the body  and  are more dangerous as  radiation is blocked by the skin. INSIDE the body an  source causes the most damage because it is the most ionising. It can enter as gas or dust. Please complete the notes on the dangers of radiation

8. Background radiation – Please copy Background radiation is low-level ionising radiation which is all around us because of radioactive material in the environment. Most is natural but a small amount is due to man-made sources such as nuclear weapon testing.

9. Radon gas Radon gas accounts for about 50% of natural background radiation. Two isotopes of radon, radon 222 and radon 220 (also known as thoron) are produced by the radioactive decay of uranium and thorium in the Earth’s crust . This gas seeps into the atmosphere sometimes building up first inside the basements and foundations of buildings. Areas containing granite and other igneous rocks, for example Cornwall, have a higher than average amount of background radiation due to radon gas. Background radiation map of England and Wales

10. Cosmic rays Cosmic rays are a form of natural background radiation produced by the nuclear reactions occurring in stars and exploding stars called supernovae. These produce high energy particles which continually bombard the Earth. Our atmosphere gives us good protection from cosmic radiation. Cosmic radiation is an issue that must be considered in proposed manned space exploration to Mars. Exposure to cosmic radiation is increased during jet travel

11. Internal radiation Internal radiation is background radiation due to radioactive sources present inside our bodies. Some of these are from naturally occurring events. An example is carbon 14 that is formed in the atmosphere by the Sun’s radiation. This behaves chemically and biologically in the same way as non-radioactive carbon 12. Others such as strontium 90 are from man-made events such as nuclear weapons testing and accidents. Strontium behaves like calcium in our bodies. We are all sources of background radiation!

12. Artificial radiation Artificial radiation is background radiation due to man-made events or procedures Some is to due leakage and accidents associated with the generation of electricity using nuclear energy. Some is due to fall-out from nuclear weapon testing. Radioactive tracers are used in industry and medicine and radioisotopes are used to treat cancer. Overall artificial radiation normally accounts for only a small percentage of background radiation. The explosion of the Chernobyl power plant in the Ukraine in 19986 placed significant radioactive isotope into the atmosphere.

13. Background radiation Please complete the questions on the sheet

14. Homework! Complete atomic structure crossword Due Tuesday 18th September

15. Detecting radioactivity – Fill in notes Radioactivity can be detected using photographic film or a Geiger counter or a cloud chamber. Radiation badge containing photographic film You need the word foggy Geiger tube and counter

16. Radiation badges Photographic film darkens on exposure to radiation and light. Light cannot penetrate the badge but ionising radiation can. Darkening of the film indicates that a person has been exposed to too much radiation. Engineer at CERN wearing a radiation badge

17. The Geiger tube Radiation produces ions in a low pressure gas between a central positively charged electrode and the outer negatively charged tube. A pulse of current then flows that is registered by the counter. The thin mica window allows the least penetrating radiation (alpha) to enter the tube. Gamma radiation and most beta can enter through the sides of the metal tube.

18. Cloud chamber • Cloud chamber • This is useful for studying alpha particles as they make visible tracks in the alcohol vapour inside

19. Activity The activity of a radioactive source is equal to the number of decays per second. Activity is measured in bequerels (Bq) 1 becquerel = 1 decay per second Henri Becquerel discovered radioactivity in 1896

20. Choose appropriate words to fill in the gaps below: Radioactivity was first discovered by Henri ___________ in 1896 when he noticed that the radiation emitted by an ore of ___________ caused the exposure of a _____________ plate. Radioactivity can also be detected using a _________ tube connected to an electronic _________ or rate meter. Background radiation is mainly due to natural sources of _________ radiation such as from ________ gas that seeps out from rocks in the ground. Becquerel uranium photographic Geiger counter ionising radon WORD SELECTION: counter Geiger photographic radon Becquerel uranium ionising

21. Online Simulations Build an atom - PhET - Build an atom out of protons, neutrons, and electrons, and see how the element, charge, and mass change. Then play a game to test your ideas! Atom builder - Freezeway.com Build an atom - eChalk Types of Radiation - S-Cool section on types of radiations including an animation of absorption and a couple of decay equations to fill in on screen. Decay series - Fendt BBC AQA GCSE Bitesize Revision: Atoms, isotopes & radioactivity - Core Science Structure of an atom Isotopes Alpha, beta & gamma radiation Penetration properties Deflection radiation Radioactive decay equations

22. Atoms and RadioactivityNotes questions from pages 199 to 208 • Describe the structure of an atom in terms of protons, neutrons and electrons and explain the meaning of symbols such as 146C. • Explain the meaning of (a) atomic number, (b) mass number and (c) isotope. • What is alpha, beta and gamma radiation? Distinguish between them in terms of their ionisation and penetration powers. • Describe the changes that occur to a nucleus when it undergoes alpha and beta decay. In each case give and example of a decay equation. • Answer the questions on pages 207 and 208. • Verify that you can do all of the items listed in the end of chapter checklist on page 207.