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Nuclear Chemistry
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Reactions Chemical Involve electrons Affected external factors (temp, pressure, catalyst) Nuclear Involve the nucleus Release WAY more energy Not affected by external factors
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Electrostatic force Interaction between charged particles Opposite charges attract Same charges repel
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How does the nucleus stay together?
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Strong Nuclear Force Attractive force that acts between all nuclear particles that are extremely close together Keeps the nucleus together Much stronger than electrostatic force!
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Radiation The emission (and transmission) of energy through space in the form of waves
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Radioactivity Alpha α Beta β Gama γ Neutron n Proton p 4 2 0 0 0 1 0 1 1
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Radioactive Any element that spontaneously emits radiation (shows signs of radioactivity) Transmutation—changing of an atom’s nucleus such that an new element is formed Alpha, beta, and proton not neutron or gamma Transuranium elements
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Why does an element go undergo transmutation?
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The stability of the nucleus depends on the neutron to proton ratio Unstable nuclei are found outside the band of stability If a nucleus is unstable, it will emit radiation (decay) to gain stability
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Radioactive decay Unstable nuclei (those that can be found outside the band of stability) losing energy by emitting radiation in a spontaneous process
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Radioisotope Isotopes of atoms with unstable nuclei and go through radioactive decay to obtain a more stable nuclei Small nuclei—up to 20 protons usually stable Exception: Carbon—14 Large nuclei—tend to be radioactive, based on the ratio of protons to neutrons; ALL nuclei with 83 protons or more are radioactive
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Nuclear Equations In a balanced nuclear equation, mass numbers and atomic numbers are conserved Example Electron capture Th Ra + He 230 90 226 88 4242 Rb + e → Kr 0 - 1 81 37 81 36
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Vocab for Equations WordLocation in the equation BombardmentReactant CaptureReactant DecayProduct Emission (emit)Product Reactant Product
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Practice 1. Zr e+ ? 2. Po He + ? 3. ? Rn + He 4. Ca e + ? 5. Cm He + ? 0 218 84 4 2 222 86 97 40 4 2 0 47 20 4 2 244 96
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Half-life Time required for ½ of a radioisotope’s nuclei to decay into its products Equation: N T = N 0 (1/2) n N T =Amount remaining at time T N 0 = initial amount n= number of half-lives
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Practice 1.Scientists start with 50.0 g sample of a radioisotope. How much is left after four half- lives?
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Practice 2.Iron-59 is used in medicine to diagnose blood circulation disorders. The half-life of iron-59 is 44.5 days. How much of a 2.000 mg sample will remain after 133.5 days?
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Carbon-14 Dating Carbon-14 is evenly spread in Earth’s biosphere Carbon-14 is radioactive and undergoes beta decay; half-life of 5730 years Dates carbon-bearing materials us to 62,000 years
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Practice
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