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Radioactivity

Radioactivity . Chapter 4: Section 1. Discovering Radioactivity . Henri Becquerel hypothesized that fluorescent minerals give off X rays. Unexpected Result . Review Page 88 to answer the following question in your notes:

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Radioactivity

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  1. Radioactivity Chapter 4: Section 1

  2. Discovering Radioactivity Henri Becquerel hypothesized that fluorescent minerals give off X rays

  3. Unexpected Result • Review Page 88 to answer the following question in your notes: • How did Becquerel discover that energy comes from Uranium, an element in the mineral?

  4. Naming the unexpected Nuclear Radiation: high energy particles and rays that are emitted by the nuclei Radioactivity: the process by which an unstable nucleus gives off nuclear radiation

  5. Kinds of Radioactivity

  6. Alpha Decay Alpha () – an atom decays into a new atom and emits an alpha particle 2 protons and 2 neutrons – the nucleus of a helium atom Mass=4Charge= + 2 Alpha particle Unstable nucleus New nucleus

  7. Alpha Decay Example: Radium-226

  8. Conservation of Decay Look at example on page 89 Mass number is conserved. Charge is conserved

  9. Beta Decay Beta () – an atom decays into a new atom by changing a neutron into a positron or a electron. Charge= -1 or +1 Mass= 0 Beta particle Unstable nucleus

  10. Two Types of Beta Decay Carbon 14

  11. Notice that the mass number is different. How many neutrons does each isotope have? 16 O 17 18 O O 8 8 8 Each isotope has 8 protons – if it didn’t then it just wouldn’t be oxygen any more. Two Types of Beta Decay An isotope is an atom with a different number of neutrons:

  12. Gamma Decay • Gamma – after  or  decay surplus energy is sometimes emitted. • Occurs when particles of a nucleus shift • The atom is not changed. No mass or charge Unstable nucleus New nucleus Gamma radiation

  13. Penetrating Power of Radiation

  14. Damage to Matter • When an organism absorbs radiation, its cells can be damaged • Radiation sickness • Fatigue and Loss of appetite • Hair loss • Death • Cancer • Radiation can also damage non-living matter

  15. Uses of Radioactivity • Isotopes are used to determine the age of objects • Smoke detectors • Tracers: radioactive elements whose paths cane be followed through a process or reaction

  16. Radioactivity in real life • Doctors use tracers to help diagnose problems • They have short half-lives and are fed or injected into patient • Follow it as it travels through the body • Isotopes can detect defects in structures • Radiation is used to detect thickness in metals

  17. Radiation Survey Annual Radiation Survey

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