Nuclear Chemistry

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Nuclear Chemistry
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Nuclear Chemistry

• The study of reactions that take place in the
  nucleii of atoms

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Chemical Reactions

• In normal chemical reactions, only the electrons
  are involved

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Radioactive Nucleii

• A nucleus that spontaneously decomposes

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Isotopes

• Elements with the same atomic number, but
  different mass number

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Isotopes

• Elements with numbers of protons, but ? numbers
  of neutrons

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Isotopes

• All elements have at least one radioactive isotope

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Radiation

• The emission of particles rays from
  spontaneously decomposing nucleii

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Modes of Decay

• Alpha emission
• Beta emission
• Gamma emission
• Positron emission
• K-electron capture

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Drill

• Name five types of radiation

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Alpha Particle (a)

• Helium nucleus
• 2 protons 2 neutrons
• mass 4 amu
• charge 2
• Penetration power small

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Beta Particle (b)

• High speed electron
• 1 electron
• mass 1/1836 amu
• charge -1
• Penetration power medium

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Gamma Ray (g)

• High energy photon
• Electromagnetic wave
• mass 0
• charge 0
• Penetration power great

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Positron (p)

• Positive electron
• 1 positive electron
• mass 1/1836 amu
• charge 1
• Penetration power medium

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K-capture

• The capture of an inner level e- by the nucleus
• 1 electron
• mass 1/1836 amu
• charge -1

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Nuclear Symbol

• Alpha 24He or 24a
• Beta -10e or 10b
• Gamma 0 0 ?
• Positron 10e
• K-electron -10e

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Fission

• The splitting of a nucleus into smaller nucleii
  involving the release of energy

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Fusion

• The combining of smaller nuclei into a larger one
  involving the release of energy

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Transmutation Rxns

• Nuclear reactions in which one element is changed
  into another

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Transmutation Rxns

• Reactions in which the nucleus of an atom is
  changed

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Transmutation Rxns

• Both fission fusion are examples of
  transmutation rxns

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Transmutation Rxns

• Can occur through emission of or bombardment by
  radioactive particles

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Transmutation Rxns

• b emission of Pm-142
• a emission of U-238
• K-capture by O-15
• p addition of O-18

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Transmutation Rxns

• a emission of U-238 followed by two separate b
  emissions

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Transmutation Rxns

• a bombardment of Th-234 followed by two separate
  b emission

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Predict Products

• a Neutron absorption by U-238 followed by two
  separate b emission

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Predict Products

• a emission of O-18 followed by a
• b emission

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Predict Products

• K-capture by V-45 followed by neutron emission
  then a emission

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Decay Rate

• The rate at which a radioactive nucleus breaks
  down

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Half-Life

• The time it takes for 50 of the radioactive
  nucleii to decompose

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Decay Rate

• Rate kdX/dt
• ln(Xo/X) kt1/2
• k 0.693/t1/2
• t1/2 half-life

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Drill

• Predict the products in each step when B-12 goes
  through a bombardment followed by b emission.

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1st Order Age Dating Formula

• t ln(Xi/Xf)t1/2
• 0.693

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• Calculate the age of a skeleton found with 0.125
  C-14 when atmospheric C-14 1.00 . t1/2 C-14
  5720 yr

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• Calculate the age of a tooth found with 0.00132
  C-14 when atmospheric C-14 1.00 . t1/2 C-14
  5720

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• Calculate the age of a bone found with 0.000300
  C-14 when atmospheric C-14 1.00 . t1/2 C-14
  5720

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Mass-Energy Relations

• DE Dmc2

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Nuclear Fact

• The mass of any nuclei is different than the sum
  of the masses of its protons neutrons

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Nuclear Fact

• The energy corresponding to the mass difference
  can be solved using
• DE Dmc2

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Binding Energy

• The energy that holds a nucleus together which
  corresponds to Dm of nucleus

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In an atomic bomb, 40.00 kg of U-235 (235.401) is
split into Ba-144 (143.223) Kr-89 (89.335) 2
neutrons (1.014). A) Calculate the energy
released. B) Calculate the wavelength of the g
ray
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Show neutron bombardment of Ra-223 followed by 3
alpha emissions