Nuclear fusion is one of the most powerful energy-producing processes known. In IB Chemistry and in broader scientific discussions, fusion helps students understand binding energy, mass defect, and why stars shine. Fusion involves combining light nuclei to form heavier ones, releasing enormous amounts of energy. This stands in contrast to nuclear fission, where heavy nuclei split apart. Mastering fusion concepts strengthens your understanding of nuclear chemistry, astrophysics, and the relationship between mass and energy.
What Is Nuclear Fusion?
Nuclear fusion is the process in which two light atomic nuclei combine to form a heavier nucleus, releasing vast amounts of energy.
Fusion typically involves isotopes of hydrogen:
- Protium (¹H)
- Deuterium (²H or D)
- Tritium (³H or T)
When these nuclei collide with enough energy to overcome electrostatic repulsion, they fuse into a more stable nucleus.
The Basic Fusion Reaction
A commonly studied reaction is the deuterium–tritium fusion:
²H + ³H → ⁴He + n + energy
This reaction produces:
- A helium-4 nucleus (alpha particle)
- A neutron
- An extraordinary amount of energy
This reaction is the basis for experimental fusion reactors.
Why Fusion Releases Energy
Fusion releases energy because the products have:
- Higher binding energy per nucleon, and
- Lower total mass than the original nuclei.
The missing mass becomes energy according to the famous equation:
