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Nuclear Chemistry

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Nuclear Symbols Element symbol Mass number, A (p + + n o ) Atomic number, Z (number of p + )

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Balancing Nuclear Equations A reactants = A products Z reactants = Z products = (1) = (0)

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Balancing Nuclear Equations #2 226 = 4 + ____ = 2 + ___ 86 Atomic number 86 is radon, Rn Rn

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Balancing Nuclear Equations # = (1) + ____ = (0) + ____ Atomic number 39 is yttrium, Y Y

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Alpha Decay Alpha production ( ): an alpha particle is a helium nucleus Alpha decay is limited to heavy, radioactive nuclei

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Alpha Radiation Limited to VERY large nucleii.

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Beta Decay Beta production ( ): A beta particle is an electron ejected from the nucleus Beta emission converts a neutron to a proton

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Beta Radiation Converts a neutron into a proton.

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Gamma Ray Production Gamma ray production ( ): Gamma rays are high energy photons produced in association with other forms of decay. Gamma rays are massless and do not, by themselves, change the nucleus

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Deflection of Decay Particles Opposite charges_________ each other. Like charges_________ each other. attract repel

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Positron Production Positron emission: Positrons are the anti-particle of the electron Positron emission converts a proton to a neutron

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Electron Capture Electron capture: (inner-orbital electron is captured by the nucleus) Electron capture converts a proton to a neutron

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Types of Radiation

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Nuclear Stability Decay will occur in such a way as to return a nucleus to the band (line) of stability. The most stable nuclide is Iron-56 If Z > 83, the nuclide is radioactive

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A Decay Series A radioactive nucleus reaches a stable state by a series of steps

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Half-life Concept

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Decay Kinetics Decay occurs by first order kinetics (the rate of decay is proportional to the number of nuclides present) N = number of nuclides remaining at time t N 0 = number of nuclides present initially k = rate constant t = elapsed time

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Calculating Half-life t 1/2 = Half-life (units dependent on rate constant, k )

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Sample Half-Lives

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Nuclear Fission and Fusion Fusion: Combining two light nuclei to form a heavier, more stable nucleus. Fission: Splitting a heavy nucleus into two nuclei with smaller mass numbers.

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Energy and Mass Nuclear changes occur with small but measurable losses of mass. The lost mass is called the mass defect, and is converted to energy according to Einsteins equation: E = mc 2 E = mc 2 m = mass defect m = mass defect E = change in energy E = change in energy c = speed of light c = speed of light Because c 2 is so large, even small amounts of mass are converted to enormous amount of energy.

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Fission

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Fission Processes A self-sustaining fission process is called a chain reaction.

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A Fission Reactor

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Fusion

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