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Some heavy elements have unstable atomic nuclei that occasionally change their chemical identity by releasing particles or energy.

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Atomic Bomb

Atomic Bomb

Credit: Charles Levy
Source: commons.wikimedia.org/wiki/File:Nagasakibomb.jpg
License: CC BY-NC 3.0

As a result of atomic fission, nuclear weapons have been and will continue to be a source of concern for everyone around the world. The mushroom cloud pictured above was taken in Nagasaki, Japan as the second of two atomic bombs was dropped during WWII. The bomb caused roughly 64,000 casualties.

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  • Fission occurs when the nucleus of a particle splits into smaller, lighter nuclei. This process releases gamma rays and extraordinarily large amounts of energy. The large amounts of energy released in an atomic bomb blast are a result of a chain reaction that happens between several uranium-235 atoms and several neutrons. 
  • Credit: Federal Government of the United States
    Source: commons.wikimedia.org/wiki/File:Uk-grable2.jpg
    License: CC BY-NC 3.0

    The result of a nuclear weapons test conducted by the United States (1953) [Figure2]

  • When energy free neutrons are absorbed by uranium-235 atoms, the nucleus splits into two atoms releasing neutrons as well as some energy equal to the binding energy. Some of the neutrons are lost while others will collide with other uranium-235 atoms. Each time a uranium-235 atoms splits, free neutrons are released to split other uranium-235 atoms as well as releasing large amounts of energy. This reaction can be seen in the following balanced equation:

  • While fission can be extremely dangerous, it also has the potential to create large amounts of usable energy. Many fission nuclear reactors use neutrons to produce fission to create an environment where a controlled amount of energy released. The amount of energy that can be harvested from nuclear fuel is a million times the amount of energy available in a similar mass of gasoline.
  • Learn more about the chain reaction that takes place: http://www.youtube.com/watch?v=mBdVK4cqiFs

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Using the information provided above, answer the following questions.

  1. Why is the mass before nuclear fission heavier than the resulting mass?
  2. Why must the rate of the fission reaction in a nuclear reactor be controlled?
  3. Is the energy produced from fission more or less dangerous than the energy produced from fusion?

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Image Attributions

  1. [1]^ Credit: Charles Levy; Source: commons.wikimedia.org/wiki/File:Nagasakibomb.jpg; License: CC BY-NC 3.0
  2. [2]^ Credit: Federal Government of the United States; Source: commons.wikimedia.org/wiki/File:Uk-grable2.jpg; License: CC BY-NC 3.0

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