5.2.2
Nuclear Fission
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Fission
Nuclear fission is a reaction in which a nucleus is split (or fissured).

Fission
- Energy is released when heavy nuclei are split apart.
- The new nuclei (daughter nuclei) have a larger binding energy per nucleon than the parent.
- This means that a large amount of energy is released (about 100 times the energy of a normal nuclear decay).

Chain reaction
- Fission occurs when an unstable atom splits, we can force this split by making the atom absorb a neutron.
- The fission reaction will produce daughter nuclei but also release energy and some neutrons.
- These neutrons will go on to cause fission reactions themselves, which will produce more neutrons.
- This is now a chain reaction.
Fusion
Nuclear fusion is a reaction in which two nuclei are combined, or fused, to form a larger nucleus.

Fusion
- We know that all nuclei have less mass than the sum of the masses of the protons and neutrons.
- When an atom is formed it releases binding energy - the greater the binding energy, the greater the missing mass.
- The binding energy per nucleon is a maximum at iron.
- This means that if two low-mass nuclei can be fused together to form a larger nucleus, energy can be released.

Making fusion work
- Fusion would release a huge amount of energy but there are many issues that need to be overcome before it will work on earth.
- The repulsion between positive nuclei is very strong and can only be overcome at very high temperatures or pressures.

Energy from fusion
- We can use the energy and mass equation:
- If we know the mass of the nuclei before and the mass of the large nucleus afterward we can find the change in mass.
- If we know the change in mass we can find the energy released.
1Space, Time & Motion
1.1Motion
1.2Forces
1.3Momentum & Impulse
2The Particulate Nature of Matter
2.1Thermal Concepts
3Wave Behaviour
3.1Oscillations
3.2Travelling Waves
3.3Wave Characteristics
3.4Wave Behaviour
3.5Standing Waves
3.6Simple Harmonic Motion
3.7Single Slit Diffraction
3.8Interference
3.9Doppler Effect
4Fields
4.1Circular Motion
4.2Newton's Law of Gravitation
4.3Fields
4.4Fields at Work
4.5Electric Fields
4.6Magnetic Effect of Electric Currents
4.7Heating Effect of Currents
4.8Electromagnetic Induction
4.9Power Generation & Transmission
5Nuclear & Quantum Physics
5.1Discrete Energy & Radioactivity
5.2Nuclear Reactions
5.3The Interaction of Matter with Radiation
6Measurements
6.1Measurements & Errors
6.2Uncertainties & Errors
6.3Vectors & Scalars
Jump to other topics
1Space, Time & Motion
1.1Motion
1.2Forces
1.3Momentum & Impulse
2The Particulate Nature of Matter
2.1Thermal Concepts
3Wave Behaviour
3.1Oscillations
3.2Travelling Waves
3.3Wave Characteristics
3.4Wave Behaviour
3.5Standing Waves
3.6Simple Harmonic Motion
3.7Single Slit Diffraction
3.8Interference
3.9Doppler Effect
4Fields
4.1Circular Motion
4.2Newton's Law of Gravitation
4.3Fields
4.4Fields at Work
4.5Electric Fields
4.6Magnetic Effect of Electric Currents
4.7Heating Effect of Currents
4.8Electromagnetic Induction
4.9Power Generation & Transmission
5Nuclear & Quantum Physics
5.1Discrete Energy & Radioactivity
5.2Nuclear Reactions
5.3The Interaction of Matter with Radiation
6Measurements
6.1Measurements & Errors
6.2Uncertainties & Errors
6.3Vectors & Scalars
Practice questions on Nuclear Fission
Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.
- 1
- 2How to Trigger Nuclear Fission:Put in order
- 3Binding energy per nucleon is highest at which element?Multiple choice
- 4Nuclear fusion requires:True / false
- 5How can we find the energy released in fusion?Multiple choice
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