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RADIATION !!!

RADIATION !!!. 7.1 Atomic Theory and Radioactive Decay. Natural background radiation exists all around us . This radiation consists of high energy particles or waves being emitted from a variety of materials. Like the sun, radio stations, Electronic devices, TV’s, cell phones, lights, etc…

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RADIATION !!!

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  1. RADIATION !!!

  2. 7.1 Atomic Theory and Radioactive Decay • Natural background radiation exists all around us. • This radiation consists of high energy particles or waves being emitted from a variety of materials. Like the sun, radio stations, Electronic devices, TV’s, cell phones, lights, etc… • Being exposed to radioactive materials can be beneficial or harmful. See pages 286 - 287

  3. X-rays, and light! • Radiation therapy (Cancer treatment) • Electricity generation (Nuclear Power plants) Beneficial(GOOD) Radiation Exposure

  4. Too much of any radiation… • Can Cause Cancer • Skin cancer from sun (UV) radiation • Body cancer from high amounts of radiation • Can cause Genetic Mutations • Radiation affects and mutates the DNA in our body cells, and then causes mutations in offspring • Can cause Radiation Sickness Harmful (BAD) Radiation Exposure

  5. Radioactivity (Radiation) is the release of high energy particles or waves. • When atoms lose high energy particles and waves, ions or even new atoms can be formed. • High energy waves and particles are called radiation when they leave the atom. What is Radiation??

  6. The higher the frequency of the radiation (ie. the shorter the wavelength) = the more harmful the Radiation is for you! The Electromagnetic Spectrum

  7. Radium (radioactive element) salts, after being placed on a photographic plate, leave behind the dark traces of radiation.

  8. (c) McGraw Hill Ryerson 2007 Searching for Invisible Rays • Radiation is everywhere, but can be difficult to detect. • Roentgen named X-rays with an “X” 100 years ago because they were previously unknown. • Becquerel realized uranium emitted seemingly invisible energy as well. • Marie Curie and her husband Pierre named this energy radioactivity. • Early discoveries of radiation relied on photographic equipment • Later, more sophisticated devices such as the Geiger counter were developed to more precisely measure radioactivity. See pages 288 - 289

  9. (c) McGraw Hill Ryerson 2007 Radioactive Decay • Unlike all previously discovered chemical reactions, radioactivity sometimes resulted in the formation of completely new atoms. • Radioactivity results from an atom having an unstable nucleus. • When these nuclei lose energy and break apart, decay occurs. • Radioactive decay releases energy from the nucleus as radiation. • Radioactive atoms release energy until they become stable, often ending up as different atoms. • An element may have only certain isotopes that are radioactive. These are called radioisotopes

  10. Radioactive Decay

  11. (c) McGraw Hill Ryerson 2007 Isotopes and Mass Number • Isotopes are different atoms of the same element, with a different number of neutrons in the nucleus. • Isotopes have the same number of protons - and therefore the same atomic number - as each other. • Isotopes of an element have the same symbol and same atomic number • By having different numbers of neutrons, isotopes have different masses, and therefore different mass numbers. • Mass number refers to the protons + neutrons in an isotope

  12. (c) McGraw Hill Ryerson 2007 Representing Isotopes • Isotopes are written using standard atomic notation. • Chemical symbol + atomic number + mass number. • Potassium has three isotopes, • Potassium is found in nature in a certain ratio of isotopes • 93.2% is potassium-39, 1.0% is potassium-40, and 6.7% is potassium-41 • Atomic mass = (.932 x 39) + (.001 x 40) + (.067 x 41) = 39.1

  13. http://www.youtube.com/watch?v=T6UujimddEc&feature=related The Atom Part 1 The Atom and Isotopes

  14. (c) McGraw Hill Ryerson 2007 Three Types of Radiation • When atoms are unstable, they break apart to become new , more stables atoms, and release radiation… there are three types that can be released. 1) Positive alpha radiation α 2) Negative beta radiation β 3) Neutral gamma radiationγ

  15. (c) McGraw Hill Ryerson 2007 Alpha Radiation  • Alpha radiation is a stream of alpha particles, . • Positively charged, 2+ • Alpha particles are the same as a helium atom. So we represent  radiation as: • Because it has two protons, it has a charge of 2+. • The release of alpha particles is called alpha decay. • Alpha particles are slow and penetrate materials much less than the other forms of radiation. A sheet of paper will stop an alpha particle. See page 294 - 295

  16. 226 222 4 Ra  Rn + He 2 88 86 ** Notice – how the Product side Atomic masses add up to the Reactant side, as well as the Atomic numbers. 225 4 ____ Ac  Fr + He 2 ___ 87

  17. (c) McGraw Hill Ryerson 2007 Beta Radiation (Beta Decay) • Beta radiation is a stream of beta particles, β. • Negatively charged, 1- • Beta particles are the same as an electron. So we represent radiation as: • Beta decay occurs when a neutron changes into a proton + an electron. The proton stays in the nucleus, and the electron is released. Therefore, the charge is -1 ( like an e-) • Beta particles are faster than alpha particles. A sheet Aluminum foil will stop an beta particle.

  18. 131 131 0 I  Xe + β -1 53 54 ** Notice – how the Product side Atomic masses add up to the Reactant side, as well as the Atomic numbers. ____ 201 0 Hg  TI + β -1 80 ___

  19. (c) McGraw Hill Ryerson 2007 Gamma Radiation • Gamma radiation, , is a ray of high energy, short-wavelength radiation. • Gamma radiation has no charge and no mass, . • Gamma radiation is the highest energy form of electromagnetic radiation. • Gamma decay results from energy being released from a high-energy nucleus., it is shown by: • It takes thick blocks of lead or concrete to stop gamma rays. • Sometimes reactions can release more than 1 type of radiation. Eg.Uranium-238 decays into an alpha particle and also releases gamma rays.

  20. Gamma Radiation See… Uranium is releasing an Alpha particle, and Gamma Radiation Nickel is decaying and giving off just Gamma Radiation Notice – no change in atomic mass or number

  21. http://www.youtube.com/watch?v=TSiNXBLfzK4 Alpha, Beta Gamma Obstruction

  22. Can you Try to figure out some Radioactive Decay questions??? 231 ____ 227 4 He Pa  Ac + ___ 89 2 91 ___ 14 14 ____ 0 N C  ___ + β -1 7 6 ___ ____ 92 143 235 0 Rb U  Cs + ___ + γ 37 ___ 0 55 92

  23. Finish Atom Part 1 http://www.youtube.com/watch?v=ekx6gz_s5VM&feature=related The Atom Part 2 http://www.youtube.com/watch?v=NP9Woxbkr_M– Nuclear Decay Song Check out some of these videos

  24. Practice problems on Pg. 295, 296 of text book Reading Check on Page 296 Check your understanding on Pg. 301 of text book – do Q’s 11, 12, 13 a,b,c Assignment

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