Balancing Nuclear Equations (OCR A Level Physics)

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Balancing Nuclear Equations

  • Nuclear reactions, such as fission and fusion, can be represented using nuclear equations (which are similar to chemical equations in Chemistry)

    For example:

Fission equation 1

  • The above equation represents a fission reaction in which a Uranium nucleus is hit with a neutron and splits into two smaller nuclei – a Strontium nucleus and a Xenon nucleus, releasing two neutrons in the process
  • In the above reaction:

    The sum of top (nucleon) numbers on the left-hand side equals the sum of top number on the right-hand side:

235 + 1 = 236 = 90 + 144 + 2 × 1

The same is true for the lower (proton) numbers:

92 + 0 = 92 = 38 + 54 + 2 × 0

  • By balancing equations in this way, you can determine, for example, the number of neutrons emitted by a process like this


Fission equation 2, IGCSE & GCSE Physics revision notesFission equation 2, IGCSE & GCSE Physics revision notes

  • In the above example, balancing the numbers on the top shows that 3 neutrons must be released in the reaction (i.e. N = 3)

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Katie M

Author: Katie M

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.