Topic: Nuclear Chemistry Aim: How do you distinguish natural and artificial transmutations? Do Now: Complete the decay equation. 239Pu _____ + _____ (Hint: Use Tables N & O, the Per. Table, & your notes from Monday) HW: Text p. 879 #1-3, 5, 7, 8 p. 886 #14
Transmutations Natural: types we already studied (wrote equations for these) – nucleus spontaneously decays to form a new element Table N radioisotopes all decay naturally (spontaneously) Give off alpha beta, or positron particles Artificial: transforming 1 element into another by bombarding the nucleus with high-energy particles Particle accelerators speed up the particles enough to cause an artificial transmutation How man-made elements are produced
Artificial Transmutations Nitrogen nucleus bombards Californium nucleus 4 neutrons given off – forms element Dubnium New element (Dubnium) is synthetic
Artificial Transmutations Tell me what’s happening in this reaction Use words like “bombard”, “emit”, etc.
How to ID Natural vs. Artificial Transmutations Artificial transmutations MUST HAVE 2 REACTANTS, whereas natural transmutations have ONLY 1 REACTANT B/C THE ELEMENT DECAYS SPONTANEOUSLY Review book p. 221 #16-23
Practical Applications – Artificial Transmutation Nuclear Energy Mass is converted into energy Energy yield is approx. 1 billion times the energy released when the same amt of a fossil fuel is burned!
Nuclear Fission Fission: nucleus of one atom splits into 2 or more pieces Hint: Fission has an “i”, so does “splits” Basic process: Nucleus is bombarded with a high-speed neutron Nucleus splits & gives off energy Lighter nuclei formed are more stable than the parent nucleus, but are often radioactive themselves. FISSION simple animation 7
Fission Chain Reaction Example: Uranium Neutrons given off as products can bombard other uranium nuclei, causing them to split as well – etc. In a controlled setting, this is a nuclear reactor that can be used for energy http://phet.colorado.edu/en/simulation/nuclear-fission (java) In an uncontrolled setting, this is atomic bomb – Manhattan Project
Nuclear Fusion Fusion: 2 light nuclei unite to form a heavier nucleus Hint: fusion has a “u”, so does unite Hydrogen bomb - 1951 Fusion Reactor Proton-Proton chain in stars
Nuclei unite – more energy Fission & Fusion High energy requirements High temperature is necessary – why? High pressure is necessary – why? Fission Fusion Similar Rxns produce energy Different Nucleus splits Nuclei unite – more energy
Sample Questions Review book p. 223 #24-33