1 Intro to Nuclear Chemistry

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<p>Intro to Nuclear Chemistry</p> <p>Chemistry Mrs. Coylehttp://www.chem.orst.edu/graduate/pics/Reactor.jpg</p> <p>How does a nuclear reactor work?</p> <p>http://www.lanl.gov/science/1663/images/reactor.jpg</p> <p>How does a small mass contained in this bomb cause Nuclear Bomb of 1945 known as fat man</p> <p>http://www.travisairmuseum.org/assets/images/fatman.jpg</p> <p>this huge nuclear explosion?</p> <p>http://library.thinkquest.org/06aug/01200/Graphics/705px-Nuclear_fireball.jpg</p> <p>Is there radon in your basement?</p> <p>http://a.abcnews.com/images/Blotter/abc_1radon_ad_070625_ssh.jpg</p> <p>Notation</p> <p>Nucleons Protons and Neutrons</p> <p> The nucleons are bound together by the strong force.</p> <p>Isotopes Atoms of a given element with: same #protons but different # neutrons</p> <p>H</p> <p>H</p> <p>H</p> <p>http://education.jlab.org/glossary/isotope.html</p> <p>Isotopes of Carbon</p> <p>Radioactive Isotopes Isotopes of certain unstable elements that spontaneously emit particles and energy from the nucleus.</p> <p> Henri Beckerel 1896 accidentally observed radioactivity of uranium salts that were fogging photographic film. His associates were Marie and Pierre Curie.</p> <p>Marie Curie: born 1867, in Poland as Maria Sklodowska Lived in France 1898 discovered the elements polonium and radium.</p> <p>http://www.radiochemistry.org/nuclearmedicine/pioneers/images/mariecurie.jpg</p> <p>Marie Curie a Pioneer of Radioactivity Winner of 1903 Nobel Prize for Physics with Henri Becquerel and her husband, Pierre Curie. Winner of the sole 1911 Nobel Prize for Chemistry.</p> <p>3 Main Types of Radioactive Decay Alpha Beta a b</p> <p> Gamma g</p> <p>Alpha DecayEmission of alpha particles a : helium nuclei two protons and two neutrons charge +2e can travel a few inches through air can be stopped by a sheet of paper, clothing.</p> <p>Alpha Decay</p> <p>Uranium</p> <p>Thorium</p> <p>Alpha Decay</p> <p>http://education.jlab.org/glossary/alphadecay.gif</p> <p>Beta Decay Beta particles b: electrons ejected from the nucleus when neutrons decay ( n p+ +b- ) Beta particles have the same charge and mass as "normal" electrons.</p> <p>Beta Decay Beta particles b: electrons ejected from the nucleus when neutrons decay n p+ +b Beta particles have the same charge and mass as "normal" electrons. Can be stopped by aluminum foil or a block of wood.</p> <p>Beta Decay</p> <p>Beta Decay</p> <p>Thorium</p> <p>Protactinium</p> <p>Gamma Decay Gamma radiation g : electromagnetic energy that is released. Gamma rays are electromagnetic waves. They have no mass. Gamma radiation has no charge. Most Penetrating, can be stopped by 1m thick concrete or a several cm thick sheet of lead.</p> <p>Examples of Radioactive DecayAlpha Decay Po Pb + He e</p> <p>Beta Decay p n + n p + e C N + e Gamma Decay Ni Ni + g (excited nucleus)</p> <p>Which is more penetrating? Why?</p> <p>Part IINuclear Stability Half-Life</p> <p>Nuclear Stability Depends on the neutron to proton ratio.</p> <p>Band of Stability</p> <p>Number of Neutrons, (N)</p> <p>Number of Protons (Z)</p> <p>What happens to an unstable nucleus? They will undergo decay The type of decay depends on the reason for the instability</p> <p>What type of decay will happen if the nucleus contains too many neutrons? Beta Decay</p> <p>Example:14 6</p> <p>C </p> <p>14</p> <p>N</p> <p>+</p> <p>0 -1</p> <p>e</p> <p>7</p> <p>In N-14 the ratio of neutrons to protons is 1:1</p> <p> Nuclei with atomic number &gt; 83 are radioactive</p> <p>Radioactive Half-Life (t1/2 ): The time for half of the radioactive nuclei in a given sample to undergo decay.</p> <p>Common Radioactive IsotopesIsotope Half-Life Radiation Emittedb, g a</p> <p>Carbon-14 Radon-222</p> <p>5,730 years 3.8 days</p> <p>Uranium-235Uranium-238</p> <p>7.0 x 108 years4.46 x 109 years</p> <p>a, ga</p> <p>Radioactive Half-Life After one half life there is 1/2 of original sample left. After two half-lives, there will be 1/2 of the 1/2 = 1/4 the original sample.</p> <p>Graph of Amount of Remaining Nuclei vs TimeA=Aoe-lt</p> <p>A</p> <p>ExampleYou have 100 g of radioactive C-14. The half-life of C-14 is 5730 years. How many grams are left after one halflife? Answer:50 g How many grams are left after two halflives?</p> <p>ProblemA sample of 3x107 Radon atoms are trapped in a basement that is sealed. The half-life of Radon is 3.83 days. How many radon atoms are left after 31 days? answer:1.2x105 atoms</p>