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Chapter 2 Nuclear physics (Chap. 30 page 745)

Chapter 2 Nuclear physics (Chap. 30 page 745). Dr. Haykel Abdelhamid Elabidi. February 2014/3 rd week of RaT 1435. Units of Chapter 30. Introduction Radioactivity Half-life. Introduction. History of Radioactivity.

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Chapter 2 Nuclear physics (Chap. 30 page 745)

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  1. Chapter 2 Nuclear physics(Chap. 30 page 745) Dr. Haykel Abdelhamid Elabidi February 2014/3rd week of RaT 1435

  2. Units of Chapter 30 • Introduction • Radioactivity • Half-life

  3. Introduction

  4. History of Radioactivity • Antoine Henri Becquerel (1852-1908) noted that uranium compounds produce invisible rays or radiation that can penetrate an opaque container. • Pierre and Marie Curie showed that uranium ores contain traces of polonium (A=84) and radium (Z=88), both much more intensely radiative than uranium.

  5. History of Radioactivity

  6. Note: This is theatomic weight, whichis the number ofprotons plus neutrons Alpha Particles (a) Example of nuclear reactions: Uranium U238 Thorium Th234 p + n n p a (4He) 92 protons 146 neutrons 90 protons 144 neutrons 2 protons 2 neutrons

  7. Beta Particles (b) Carbon C14 Nitrogen N14 + e- electron (beta-particle) 6 protons 8 neutrons 7 protons 7 neutrons We see that one of the neutrons from the C14 nucleus “converted” into a proton, and an electron was ejected. The remaining nucleus contains 7p and 7n, which is a nitrogen nucleus. In symbolic notation, the following process occurred: n  p + e ( + n ) - faster than alpha particles, penetrate light materials, 10 mm of wood, 3 mm of Al

  8. Gamma particles (g)Gamma rays are high-frequency electromagnetic radiations (i.e. photons) which do not carry any charge. A nucleus can be in an excited state, as electrons in the atom. Neon Ne20 Neon Ne20 + 10 protons 10 neutrons(lowest energy state) gamma 10 protons 10 neutrons(in excited state) • very fast and able to penetrate most materials such a 7 cm of lead • can be harmful to our bodies, suffer structural damage • - It is NOT visible by your naked eye because it is not in the visible part of the EM spectrum.

  9. Half-life (T)

  10. Half-life (T)

  11. Half-life (T)

  12. Half-life (T) Solution Example 30.1 page 747:

  13. Effective half-life

  14. Effective half-life Solution Example 30.2 page 748:

  15. Homeworks: Exercises 30.1; 30.2; 30.3; 30.5; 30.7 page 762 Thank you for your attention See you next time Inchallah

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