1. Nuclear Chemistry Standard # 11- Nuclear Processes Mr. Colón 2012-2013

2. Nuclear Chemistry StabilityApplications The study of reactions in which nuclei of unstable isotopes gain stability by undergoing changes. These reactions are traditionally accompanied by emission of large amounts of energy. Are not affected by changes in temperature, pressure, or catalysts. Cannot be slowed down, speeded up, or turned off.

3. Stability Depends on the neutron-to-proton ratio and size of nucleus. Isotope= a twin sibling. Radioisotope= radioactive twin sibling. Radioactive Decay

4. Applications Radiation is a part of Life. Geiger counter, scintillation counters, and film badges are used to detect the presence of radiation. FissionFusion Uses Transmutation

5. Radioactive Decay An unstable molecule loses energy by emitting radiation and eventually unstable radioisotopes are transformed into stable (non radioactive) isotopes. Spontaneous and no energy is required. AlphaBetaGammaHalf-Life Particle Names

6. Particle Names Helium atom (alpha) Electron(beta) Proton Positron Neutron

8. Alpha-  The process in which a helium atom is ejected or emitted from the nucleus. Can easily be stopped by a sheet of paper. 238 234 4 U  Th + He 92 90 2

9. Beta-  The process in which an electron is ejected or emitted from the nucleus. Beta particles are stopped by aluminum foil or thin pieces of wood. Has three different modes of decay: electron emission, electron capture, and positron emission. Electron Emission Electron Capture Positron Emission

10. Gamma-  High-energy electromagnetic radiation given off by a radioisotope. Does not have mass and no electrical charge. Can be stopped, although not easily, by several meters of concrete or several centimeters of lead.

11. Half-Life Every radioisotope has a characteristic rate of decay measured by its half-life. Time required for one-half of the nuclei of a radioisotope sample to decay to atoms of a new element.

12. Fission Splitting of the nucleus into smaller fragments. (Nuclear Reactors) Energy from 1kg U-235 = 20,000 tons of dynamite. Spontaneous Fission- in which the parent nucleus splits into a pair of smaller nuclei and usually accompanied by an ejection of one or more neutrons. Spontaneous Fission

13. Fusion Nuclei combine to produce a nucleus of greater mass. (hydrogen bomb) More energy than fission. Drawbacks: High temperatures of 40,000,000 °C required to start reaction and containment once reaction starts. Products usually not radioactive. 2 3 4 1 H + H  He + n + energy 1 1 2 0

14. Uses Diagnose diseases Cancer treatment Tracers/Labelers Art forgeries Gun Powder residue detection Carbon dating

15. Transmutation

16. Electron Emission 40 40 0 K  Ca + e 19 20 -1

17. Electron Capture 40 0 40 K + e  Ar + h 19 -1 18

18. Positron Emission 40 40 0 K  Ar + e 19 18 +1

19. Spontaneous Fission 252 140 108 1 Cf  Xe + Ru + 4 n 98 54 44 0