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Nuclear Chemistry. Deals with the nucleus of the atom (protons & neutrons) Matter is changed into energy by the breaking up of the nucleus of an atom Mass defect – The difference in the calculated mass of an atom and the measured mass of an atom Mass of neutron = 1.67493x10 -27 kg
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Nuclear Chemistry • Deals with the nucleus of the atom (protons & neutrons) • Matter is changed into energy by the breaking up of the nucleus of an atom • Mass defect – The difference in the calculated mass of an atom and the measured mass of an atom • Mass of neutron = 1.67493x10-27kg • Mass of proton = 1.67262x10-27 kg • Nuclear Binding Energy – amount of energy needed to break up the nucleus = a measure of the stability of the nucleus • E = mc2
Practice Calculate the binding energy of for carbon -12 (atomic mass 12.000) and uranium-235 (atomic mass 235.0439). The atomic mass of 11H is 1.00782 amu and the mass of a neutron is 1.00866 amu.
Band of stability Looks at the proton/neutron ratio • The preferred ratio of p+/n0 is 1:1 • Atoms with low atomic #s have close to that ratio • Larger atoms (atomic #s 84+) do not so they are radioactive Atoms with a high p+/n0 - emit- particles Atoms with a low p+/n0 - +emission or e-capture Atomic #s 84+ - emission
Types of Decay Emission(given off) • - alpha – 42He Weakest type 2. - - beta particle – 0-1e 3. - gamma ray – energy Strongest type 4. + - positron – 0+1e Capture(taken in) 1. 0-1e – electron is taken in
Nuclear Equations • Equations written to represent the splitting that takes place in the nucleus (called a transmutation) • The sum of the atomic #s of products = sum the atomic #s of reactants • The sum of the mass #s of products = sum of the mass #s of the reactants 116C 115B + 01 116C + 0-1e 115B 146C 147N + 0-1 19278Pt 18876Os + 42He
Transmutations • The splitting of the nucleus • Larger atoms split spontaneously b/c they are radioactive • Others can be induced (forced) to occur by hitting a nucleus with a particle (nuclear fission) 23592U + 10n 9336Kr + 14056Ba + 310n Shortened notation = 23592U (10n, 310n) 9336Kr, 14056Ba
Practice Complete the following nuclear equations. • 73Ga 73Ge + _____ • 192Pt 188Os + ____ • 205Bi 205Pb + ____ • 241Cm + ____ 241Am • ______ + 42He 24397Bk + 10n • 24998Cf + _____ 260105Db + 410n
Practice One type of commerical smoke detector contains a minute amount of radioactive americium-241 which decays by particle production. The particles ionize molecules ini the air, allowing it to conduct an electric current. When smoke particles enter, the conductivity of the air is changed and the alarm buzzes. • Write the equation for the decary of americium-241 by particle production. b. The complete decay of 241Am involves successively , , , , , , , , , , , and . What is the final stable nucleus produced in this decay series?
Half - Life • The time it takes for ½ of a radioactive material to decay
Nuclear Fission • The splitting of nucleus into smaller nuclei • Takes place in power plants
Nuclear Fusion • Smaller nuclei combining to form a large one • HUGE amounts of energy involved • Sun, Hydrogen bomb