Notes Ch' 18

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Notes Ch. 18

• Nuclear Chemistry

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18-1 Nuclear Stability Radioactive Decay (
Natural transmutation)

• A.    Certain isotopes are unstable and emit
  radiation. Know the decay particles from
  handout.
• 1.    Natural isotopes (Uranium-238)
• 2.    Artificial isotopes (Plutonium-239)

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18-1 Radioisotopes cont

• AB.   Half-life the time it takes for ½ of a
  sample of a given isotope to decay.
• Potassium-40 ½ life 1.3x109 years
• AC.   Radiocarbon dating- How is it used to date
  once living material?
• Carbon-14 ½ life5730 years.
• Only good to about 30,000 years. Why?

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18-2 Transmutation

• A. Artificial Transmutation Nuclear
  bombardment reactions change stable nuclei into
  unstable ones. Creates new elements or new
  radioactive isotopes.

B. Particle accelerators- devices used to study
collisions of particles at or near the speed of
light.
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24-2 Biological Effects of Radiation

• A. Units of Radiation
• 1.  curie- of disentegrations per second from 1
  g of radium. Doesnt consider type of radiation.
• 2.  rad absorbed dose of radiation doesnt
  consider type or effect.
• 3.  rem roentgen equivalent man measures the
  energy transferred by radiation and the bodies
  sensitivity to that radiation.
• 4.  dosimeter instrument used to detect
  radiation exposure. Some use photographic film.
•  

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24-2 Biological Effects of Radiation cont

• A.   SI Units
• 1. gray (Gy) - one joule of energy per kilogram
  of body tissue (100 rad)
• 2. sievert (Sv) exposure equal to one gray of
  gamma (?) radiation (100 rem)
•  
• B.    Effects of radiation
• 1. Ionization strips electrons from atoms.
  Creating free radicals that disrupt living cells

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24-2 Biological Effects of Radiation cont

• A.    Types of damage
• Somatic damage damage to the organism that
  received the dose. (cancer)
• Genetic damage damage to reproductive organs or
  offspring. (mutation)
•     Detecting radiation Geiger counter
•  

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24-2 Biological Effects of Radiation cont

• A.    Beneficial uses of radiation
• 1. radiotracers (barium) used to follow
  substances as they move through a system.
• 2. Cancer treatment radiation therapy
• 3. Food preservation- read handout for discussion

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24-3 Harnessing the Nucleus

• A . Nuclear Fission splitting the atom
• 1.    A large nucleus is split into smaller
  nuclei of approximately equal mass
• 2.    Mass is converted into energy Emc2
• 3.    Nuclear chain reactions occur when a
  critical mass is reached that results in the
  neutrons emitted during fission splitting other
  nuclei.
• 4.    Nuclear reactors use fission reactions to
  heat water and the steam turns a turbine
  connected to a generator.
• 5.    Radioactive waste is a necessary bi-product
  of using fission to produce energy. Waste
  disposal is a huge issue.

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24-3 Harnessing the Nucleus cont

• A.    Nuclear Fusion- colliding nuclei merge
• 1.    Plasma the 4th state of matter is
  produced when smaller nuclei join to form larger
  nuclei. Requires extremely high temperatures.
• 2.    Mass is lost in fusion reactions. This
  lost mass is converted into energy. Emc2
• 3.    Fusion research could remove dependence
  on fossil fuels and polluting energy production.