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Nuclear Chemistry "in recognition of the extraordinary services he has rendered by his discovery of spontaneous radioactivity” Nobel Prize in Physics 1903 Henri Becquerel Pierre Curie Marie Curie What causes radiation or nuclear decay? The presence of too few or too many neutrons compared to protons leads to an unstable nucleus. Reminder Mass number=Protons + Neutrons 15 7 Atomic number=Protons N Radioisotopes Radioisotopes Isotopes that have an unstable nucleus Nuclear Reactions and Radiation. Nuclear Reactions: Reactions in which Radiation : These changes are accompanied Transmutation: the conversion of one radioisotopes gain stability by undergoing changes. by the release of large amounts of energy. chemical element or isotope into another through nuclear reaction. Radioisotope Nuclear Reaction Radiation Radioactive Decay Radioactive Decay - The process where an unstable nucleus loses energy by emitting particles of radiation. Alpha Decay Consists of a helium nuclei that has been emitted from a radioactive source. 4 Symbol: Example: 230 90 Th He 2 226 88 Ra 4 2 He Beta Decay A neutron is converted to a proton and an electron. The electron is emitted, the proton stays. 0 Particle Emitted: 1 Symbol: Example: e 14 6 C 14 7 N 0 1 e Gamma Radiation Gamma radiation is emitted often times along with alpha and beta radiation. It has no mass or electrical charge. It is high energy radiation and is very dangerous! Particle: Symbol: Radioactive particles Penetrating power: Summary Property Alpha Radiation Beta Radiation Gamma Radiation Composition (Helium Nucleus) Electron High energy electromagnetic radiation Symbol 4 2 He 0 1 e γ Charge 2+ 1- 0 Mass 4 1/1837 0 Radium-226 Carbon-14 Cobalt-60 Low Moderate Very high Paper, clothing Metal foil Lead, concrete Common Source Penetrating Power Shielding Complete page 18 for Homework Radioactivity and Radioactive Decay Today’s Objective 1. 2. Write nuclear decay equations to depict the nuclear decay of radioisotopes. Predict the type of nuclear decay using the band of stability. How do we write nuclear equations? A nuclear equation will look like this: 1. Isotope particle + element Because of the law of conservation of mass, all mass numbers and atomic numbers, or the tops and bottoms of the complete symbols, must balance on either side of the arrow. 2. When you write your equation, balance your mass numbers followed by your atomic numbers. Nuclear Equations (cont) Beta Decay 42 19 K Gamma Decay 0 -1 e 42 20 Ca K 37 18 42 = 0 + 42 and 19 = -1 + 20 Emitted along with Alpha and Beta Radiation. Does not change the element. 42 19 Change from 0 -1 e 42 20 Ca 42 = 0 + 42 + 0 and 19 = -1 + 20 + 0 Ar Writing Nuclear Decay Equations Nuclear Equations: Practice 1. 2. 3. C C 14 6 0 0 14 6 Word Equations 4. Write the equation of lead-210 undergoing alpha decay. 5. Write the equation where lead-210 emits a beta particle. 6. Show the transmutation of uranium-237 as it undergoes alpha decay. What is the nuclide that is produced? Homework: page 20 Transmutation •The process where a nucleus becomes a NEW nucleus because the number of protons has been changed. •What is the only type of radiation that does NOT change the atomic number? Gamma (λ)- it has 0 mass and 0 charge, therefore does not affect the nucleus size! Fission and Fusion Show “Nuclear Power and Its Effect on the World” http://www.youtube.com/watch?v=ur6Kb62Ci5k Fission and Fusion Fission Fusion Bombard nuclei with neutrons Atom falls apart Lots of energy evolved Can create a chain reaction Instantaneous Ex:Atomic Bombs, nuclear reactors Requires input of energy Two nuclei combine to make new atom of Helium Releases more energy than fission Difficult to control Ex: Sun uses fusion Fission Reaction/ Chain Reaction FUSION Nuclear Power In the News!!!!! 60 Minutes Report Fukushima Nuclear Power Plant Japan http://www.youtube.com/watch?v=z6cYE7PwMik