Fission and Fusion in Chemistry
Nuclear reactions release far more energy than chemical ones.
About this topic
Nuclear reactions release millions of times more energy per atom than chemical reactions because they involve the strong force in the nucleus. Fission splits large nuclei such as uranium-235 into smaller ones when struck by a neutron, releasing more neutrons that can trigger a chain reaction. Fusion joins light nuclei, such as hydrogen isotopes, into helium, powering the Sun.
The energy comes from a small loss of mass, converted according to Einstein's equation E = mc squared. Binding energy per nucleon peaks near iron, so splitting very heavy nuclei or joining very light ones both move toward more stable nuclei and release energy. In a reactor, control rods absorb neutrons to keep the chain reaction steady; in a bomb, it runs away. Fusion needs temperatures of millions of degrees to overcome the repulsion between positive nuclei.
One kilogram of uranium-235 releases energy comparable to about 2,000 tonnes of coal. Fission supplies about ten percent of the world's electricity with no carbon dioxide from operation, but produces long-lived waste. Fusion produces little waste and uses plentiful fuel, but sustaining it on Earth is a huge engineering challenge.
A misconception is that fusion and fission are the same; one splits, one joins. Another is that nuclear power plants can explode like bombs, which their design prevents.
Key ideas
- Fission splits large nuclei
- Fusion merges small ones
- Mass defect becomes energy
Quick check
Use cases: where Fission and Fusion in Chemistry helps
- Homework: review the key idea behind Fission and Fusion in Chemistry before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Fission and Fusion in Chemistry without notes.
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- Teaching a friend: explain Fission and Fusion in Chemistry in your own words, then compare your version with the key ideas.
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Frequently asked questions
What is Fission and Fusion in Chemistry?
Nuclear reactions release far more energy than chemical ones.
What will I learn in Fission and Fusion in Chemistry?
Fission splits large nuclei. Fusion merges small ones. Mass defect becomes energy.
Is Fission and Fusion in Chemistry part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Fission and Fusion in Chemistry lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Fission and Fusion in Chemistry?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
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