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Binding energy per nucleon
Intermediate
Peaks near iron; explains fission and fusion.
The curve rises quickly to about 8.8 MeV at iron-56 and slowly falls for heavy elements. Fusion of light nuclei and fission of heavy nuclei both move toward the peak and release energy.
Iron-56 is the most stable.
Helium-4 is unusually stable.
In more detail
Binding energy per nucleon peaks near iron-56 and nickel-62. Lighter nuclei can gain energy by fusion, and heavier nuclei by fission, moving towards the peak.
Real-world uses
- Explains why fusion powers stars and fission powers reactors.
- Predicts which nuclear reactions release energy.
- Nuclear engineers use the binding energy curve to show why both fission of heavy nuclei and fusion of light ones release energy.
Open the interactive lesson, with simulation and quiz →
Frequently asked questions
Why is iron special?
It has the highest binding energy per nucleon, so it is among the most stable nuclei.
Does the curve explain fission and fusion?
Yes, both processes move nuclei towards higher binding energy per nucleon.
Why does iron have the highest binding energy per nucleon?
Iron nuclei are at the most stable point on the curve, so neither splitting nor joining iron releases energy.
Related topics in Atomic & Nuclear Physics
Nuclear density · Mass defect · Binding energy · Nuclear force · Radioactivity discovery · Alpha decay