1. 5.2 - Nuclear Chemistry

2. When you think of nuclear chemistry, what do you think of?
Fat man fission bomb – Nagasaki, Japan Plutonium
Little Boy fission bomb –Hiroshima, Japan Uranium

3. Nagaski

4. Chernobyl, Ukraine 1986

5. Nuclear Chemistry
Nuclear Chemistry – the study of changes occurring in the nucleus of atoms

6. Types of radiation
Alpha () particle  Helium (He) nucleus (2 protons and 2 neutrons)
+2 charge, mass # = 4amu
poor penetrating ability
ionize molecules that they contact

7. Types of radiation Beta () particles charge of –1; negligible mass
high penetrating ability; lower ionization ability than  particles
produced by change of neutron to proton

8. Types of radiation Gamma Rays Electromagnetic Rays
High penetrating and ionization
Higher than both  and  particles

11. Radioisotopes No stable isotopes above atomic numbers 83 (Bismuth)
Isotopes with unstable nucleus are radioisotopes
Radioisotopes will naturally lose part of their nucleus by radioactive decay
Radioisotopes decay at different rates

12. Transmutation
Transmutation – the change of an atom from one element to another
Radioactive Decay Series – A series of Transmuations eventually ends with a stable element
U-238 decay series
U-238 will emit  and  particles in a series of nuclear reactions ending with Pb-206.
*Nuclear Reactions involve a change in mass, charge or both

13. 2.  emission
U-238 decays by  emission to produce Th-234
Equation

14.  emission Th-234 is also unstable and will emit a  - particle
The series continues through 12 more transmutations until the atom ends as a stable atom of Pb-206

16. Equation The Law of Nuclear Equations
Charge and mass must be equal on both sides of the equation

17. Nuclear Fission
Nuclear Fission – splitting of atomic nuclei in fragments
Releases large amounts of energy
Example U-235 is bombarded with neutrons and splits to produce Ba-141;Kr-92 and 3 neutrons
The three neutrons released can split other U-235 nuclei (chain reaction)
Critical Mass – the amount of substance required to sustain a chain reaction

20. Pro’s – high energy; low waste; available fuel
Nuclear Fusion – 2 or more light nuclei combine to form a nucleus with slightly less total mass
Fusion requires high energy to overcome repulsion of nuclei
Pro’s – high energy; low waste; available fuel
Con’s – extreme temperature; contain vessel; heat pollution

22. Uses of radioisotopes
Tracers – the movement of radioisotopes that can be traced through an organism
Gamma radiation used to destroy bacteria and fight cancer cells
Radioactive Dating – using half-life of radioisotopes to date relics
U-238; C-14
Ratio of C-12 of C14 changes after an organism dies. By comparing this ratio to the set ratio in the environment we can determine the relative age of organic matter

24. Particle accelerations – accelerate particles used to “bombard” atoms and induce radioactivity
Fuel – nuclear energy

25. Particle Accelerators