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Intro to Nuclear Chemistry. Chemistry. http://www.chem.orst.edu/graduate/pics/Reactor.jpg. How does a subatomic particle cause damage to human tissue?. http://studentsagainstclimatechange.blogspot.com/2007/12/final-exchange-with-donna-dillman-after.html. Isotopes of Carbon.

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intro to nuclear chemistry

Intro to NuclearChemistry

Chemistry

http://www.chem.orst.edu/graduate/pics/Reactor.jpg

how does a subatomic particle cause damage to human tissue
How does a subatomic particle cause damage to human tissue?

http://studentsagainstclimatechange.blogspot.com/2007/12/final-exchange-with-donna-dillman-after.html

radioactive isotopes
Radioactive Isotopes
  • Isotopes of certain unstable elements that spontaneously emit particles and energy from the nucleus.
  • Henri Beckerel 1896 accidentally observed radioactivity of uranium salts that were fogging photographic film.
  • His associates were Marie and Pierre Curie.
marie curie a pioneer of radioactivity
Marie Curie a Pioneer of Radioactivity
  • Winner of 1903 Nobel Prize for Physics with Henri Becquerel and her husband, Pierre Curie.
  • Winner of the 1911 Nobel Prize for Chemistry.
  • 1898 discovered the elements polonium and radium.
alpha decay
Alpha Decay

Emission of alpha particles a :

  • helium nuclei
  • two protons and two neutrons
  • charge +2e 
  • can travel a few inches through air
  • can be stopped by a sheet of paper, clothing.
alpha decay1
Alpha Decay

Uranium Thorium

alpha decay2
Alpha Decay

http://education.jlab.org/glossary/alphadecay.gif

beta decay
Beta Decay
  • Beta particles b: electrons ejected from the nucleus when neutrons decay

n -> p+ +b-

  • Beta particles have the same charge and mass as "normal" electrons.
  • Can be stopped by aluminum foil or a block of wood.
beta decay1
Beta Decay

Thorium Protactinium

gamma decay
Gamma Decay
  • Gamma radiation g : electromagnetic energy that is released. 
  • Gamma rays are electromagnetic waves.
  • They have no mass.
  • Gamma radiation has no charge.
    • Most Penetrating, can be stopped by 1m thick concrete or a several cm thick sheet of lead.
examples of radioactive decay
Examples of Radioactive Decay

Alpha Decay

Po  Pb + He

Beta Decay p n + e

n  p + e

C  N + e

Gamma Decay

Ni  Ni + g

(excited nucleus)

radioactive half life t 1 2
Radioactive Half-Life (t1/2 ):
  • The time for half of the radioactive nuclei in a given sample to undergo decay.
common radioactive isotopes
Common Radioactive Isotopes

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

radioactive half life
Radioactive Half-Life
  • After one half life there is 1/2 of original sample left.
  • After two half-lives, there will be

1/2 of the 1/2 = 1/4 the original sample.

example
Example

You have 100 g of radioactive C-14. The half-life of C-14 is 5730 years.

  • How many grams are left after one half-life? Answer:50 g
  • How many grams are left after two half-lives?
problem
Problem

A sample of 3x107 Radon atoms are trapped

in a basement that is sealed. The half-life of

Radon is 3.83 days. How many radon atoms

are left after 31 days?

answer:1.2x105 atoms

energy in nuclear reactions
Energy in Nuclear Reactions
  • There is a tremendous amount of energy stored in nuclei.
  • Einstein’s famous equation, E = mc2, relates directly to the calculation of this energy.
  • In chemical reactions the amount of mass converted to energy is minimal.
  • However, these energies are many thousands of times greater in nuclear reactions.
nuclear fission
Nuclear Fission
  • How does one tap all that energy?
  • Nuclear fission is the type of reaction carried out in nuclear reactors.
nuclear fission1
Nuclear Fission
  • Bombardment of the radioactive nuclide with a neutron starts the process.
  • Neutrons released in the transmutation strike other nuclei, causing their decay and the production of more neutrons.
  • This process continues in what we call a nuclear chain reaction.
nuclear fission2
Nuclear Fission
  • If there are not enough radioactive nuclides in the path of the ejected neutrons, the chain reaction will die out.
  • Therefore, there must be a certain minimum amount of fissionable material present for the chain reaction to be sustained: Critical Mass.
nuclear reactors
Nuclear Reactors

In nuclear reactors the heat generated by the reaction is used to produce steam that turns a turbine connected to a generator.

nuclear reactors1
Nuclear Reactors
  • The reaction is kept in check by the use of control rods.
  • These block the paths of some neutrons, keeping the system from reaching a dangerous supercritical mass.
nuclear fusion
Nuclear Fusion
  • Fusion would be a superior method of generating power.
  • It occurs when small nuclei combine – releasing much more energy than fission.
    • The products of the reaction are not radioactive.
    • The material must be in the plasma state at several million kelvins.
    • Tokamakapparati, using magnetic fields to heat the material, show promise for carrying out these reactions.