Ch. 19 -- Nuclear Chemistry

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Ch. 19 -- Nuclear Chemistry
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Discovery of Radioactivity http//www.radiation-sc
ott.org/timeline/table.htm

• Radioactivity was first observed in 1896 by the
  French scientist Henri Becquerel. He discovered
  that Uranium salts would fog up a photographic
  plate.
• In 1898, Marie Curie and her husband Pierre
  coined the term radiation and radioactivity and
  went on to discover several new elements
  Polonium and Radium.
• She went on to win 2 Nobel Prizes 1903 in
  Physics 1911 in Chemistry, but she died of
  cancer caused by radiation exposure in 1934 at
  the age of 66.
• Her husband died in 1906 after getting hit by a
  horse and buggy.

Marie Curie
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Nuclear Reactions

• Nuclear reactions involve the nucleus instead of
  the electrons as in a regular chemical reaction.
• The instability of the nucleus of a radioactive
  element causes the of protons and neutrons to
  change.
• Some of the mass can be converted into a
  tremendous amount of energy shown by a very
  famous equation
• Emc2
• Energy (mass)x(speed of light)2
• c 3.0 x 108 m/s

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What makes a nucleus stable or unstable?

• It depends on the p and no ratio.
• Z Atomic p
• A Mass no p
• Nucleons are just the particles in the nucleus.

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Chemical vs. Nuclear Reactions
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Nuclear Reactions Radiation

• Nuclear reactions release 3 main types of
  radiation
• (a) Alpha Particles helium nucleus (2 p and 2
  n0)
• (ß) Beta Particles high energy electrons
• (?) Gamma Rays high energy electromagnetic
  radiation

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Other Sources of Radiation
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Effects of Radiation
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Balancing Nuclear Reactions

• In chemical reactions the elements stay the same.
  
• In nuclear reactions, the elements change but the
  mass s and atomic s are conserved.
• Alpha Emission
• Beta Emission

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Alpha Decay
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Beta Decay
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Another type of nuclear reaction is electron
capture where an atom absorbs one of its own
electrons.
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Positrons They are just like an electron, but
they have a () charge instead of a negative
charge.
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Types of Decay--Summary
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Nuclear Fission

• In fission, the nucleus splits apart. (Fission is
  division.)

• Atom bombs and nuclear power plants use fission
  of U-235 .

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Nuclear Fission Chain Reaction
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Detecting Radiation
When the argon gas is hit by a particle, it
ionizes and produces a currentclick.
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Detecting Radiation Geiger Counter
When the argon gas is hit by a particle, it
ionizes and produces a currentclick.
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Nuclear Power

• Currently about 103 nuclear power plants in the
  U.S. and about 435 worldwide.
• 17 of the worlds energy comes from nuclear.
• There are 6 nuclear power plants in Illinois.
  The closest one to us is in Clinton.

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Clinton, IL Nuclear Power Plant
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1000 MegaWatt Power Plant Pollution Coal-Fired
vs. Nuclear
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Diagram for the tentative plan for deep
underground isolation of nuclear wasteYucca Mt.
Nevada
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Nuclear Power Plants

• Nuclear power plants use the heat of a controlled
  nuclear fission reaction to boil water that makes
  steam which turns a turbine and that produces
  electricity.

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Schematic of the Reactor Core
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Nuclear Power Plant Disasters

• One possible type of reactor disaster is known
  as a meltdown. In such an accident, the fission
  reaction goes out of control, leading to the
  emission of great amounts of radiation.

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• In 1979, the cooling system failed at the Three
  Mile Island nuclear reactor near Harrisburg,
  Pennsylvania. Radiation leaked, forcing tens of
  thousands of people to flee. The problem was
  solved minutes before a total meltdown would have
  occurred. Fortunately, there were no deaths.

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• In 1986, a much worse disaster struck Russia's
  Chernobyl nuclear power plant. In this incident,
  a large amount of radiation escaped from the
  reactor. Hundreds of thousands of people were
  exposed to the radiation. Several dozen died
  within a few days. In the years to come,
  thousands more may die of cancers induced by the
  radiation.

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Chernobyl Sarcophagus
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Nuclear Fusion

• In Fusion, nuclei combine to form a heavier
  nucleus.
• When the p and n0 bind, this releases tremendous
  amounts of energy.
• Nuclear fusion occurs in the sun and other stars.

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Spiderman 2Tritium
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Uses of Nuclear Radiation

• Medicine imaging and tumor treatments

Thyroid imaging using Tc-99
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Food Irradiation

• Food can be irradiated with gamma rays from 60Co
  or 137Cs.
• Irradiated milk has a shelf life of 3 months
  without refrigeration.
• USDA has approved irradiation of meats and eggs.

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1000-10,000 kilorads
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• Radiocarbon Dating--The radioactivity of a
  sample can be used to determine how old it is.
• Half-life The time for half of the nuclei to
  decay.

Isotope Half-Life Radiation
Emitted Carbon-14 5,730 years b,
g Radon-222 3.8 days a Uranium-235 7.0 x
108 years a, g Uranium-238 4.46 x 109 years
a
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Half-Life Graph
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The times given in this table are the half-life
values for the decay of U-238 into Pb-206.
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Transuranium Elements Beyond 92