1. Alpha Beta Gamma

2. Lesson Contents 1.What is Radioactivity? 2.Physical properties of ,  and  3.Penetrating power of ,  and  4.N v Z  graphs (for fun) 5.Decay laws

3. Early Pioneers in Radioactivity Roentgen: Discoverer of X-rays 1895 Becquerel: Discoverer of Radioactivity 1896 The Curies: Discoverers of Radium and Polonium 1900- 1908 Rutherford: Discoverer Alpha and Beta rays 1897 Villard: Discovery of gamma rays 1898-1900

4. What do we mean by Radioactivity? Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. The general idea: An unstable nucleus releases energy to become more stable

5. Radioactivity – Is it a Health Problem? The Alpha, Beta and Gamma particles all add energy to the body’s tissues. It can alter DNA.

6. http://www.youtube.com/watch?v=5oUagoF_viQ

7. Alpha Radiation Alpha particles contain two protons and two neutrons

8. Alpha Radiation  has the same constitution as a Helium nucleus Alpha particles may be written as

9. Beta-minus Radiation Beta-minus particles are electrons

10. Beta-minus Radiation  - is produced when a neutron decays Beta-minus particles may be written as

11. Beta-minus Radiation  - is produced when a neutron decays The surplus mass is released as kinetic energy in the  - and as an antineutrino

12. Hulk SMASH!!!! http://www.youtube.com/watch?v=jv95T- 5bSYkhttp://www.youtube.com/watch?v=jv95T- 5bSYk

13. Gamma Radiation Gamma rays are a form of electro- magnetic radiation

14. Gamma Radiation  release is often associated with  or  decay Gamma rays remove energy from an unstable nucleus. Has no mass and no charge. O O

15. Penetrating power

16. http://www.youtube.com/watch?v=5oUagoF_viQ

17. N v Z graphs A Graph of neutron number (N) against proton number (Z) helps to predict whether an isotope will emit  or  - radiation

18. N v Z graphs Isotopes in this region emit  particles to become more stable. N decreases by 2 Z decreases by 2

19. N v Z graphs Isotopes in this region emit  particles to become more stable. N decreases by 1 Z increases by 1

20. Decay laws - alpha When an isotope emits an  particle  Its nucleon number decreases by 4  Its proton number decreases by 2 For example:

21. Decay laws – beta-minus When an isotope emits a  - particle  Its nucleon number is unchanged  Its proton number increases by 1 For example:

22. Decay laws Try writing the nuclear equations for the decay of these isotopes

23. Decay laws Answers

24. 2 6 14 28 50 82 126

25. Stability is not usually achieved in a single step Stability is not usually achieved in a single step When a radioactive nucleus reaches a stable state by a series of steps, we call it a decay series When a radioactive nucleus reaches a stable state by a series of steps, we call it a decay series

28. Hulk sad the PowerPoint is over, Hulk no wanna leave.