Nuclear Fission and Fusion
Nuclear reactions release enormous amounts of energy from changes to atomic nuclei. Fission splits heavy nuclei; fusion joins light nuclei. Both power stars, and fission powers nuclear plants.
What You Need to Know
Key Concept Diagram
Nuclear fission splits a heavy nucleus (e.g. uranium-235) into smaller fragments, releasing energy
Nuclear fusion joins light nuclei (e.g. hydrogen) to form a heavier nucleus, releasing even more energy
Both reactions release energy according to Einstein's E = mc^2
The Sun produces energy through nuclear fusion of hydrogen into helium
Key Vocabulary
Nuclear fission
The splitting of a heavy atomic nucleus into smaller nuclei, releasing large amounts of energy
Nuclear fusion
The joining of two light nuclei to form a heavier nucleus, releasing enormous energy
Chain reaction
A self-sustaining sequence of fission reactions in which neutrons from each reaction trigger further reactions
E = mc^2
Einstein's equation relating mass and energy; small amounts of mass convert to enormous energy
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
How does a nuclear power plant generate electricity?
Question 2
Which reaction powers the Sun?
Question 3
Why does nuclear fusion release more energy than fission?
Key Concepts Summary
- ●Nuclear fission splits a heavy nucleus (e.g. uranium-235) into smaller fragments, releasing energy
- ●Nuclear fusion joins light nuclei (e.g. hydrogen) to form a heavier nucleus, releasing even more energy
- ●Both reactions release energy according to Einstein's E = mc^2
- ●The Sun produces energy through nuclear fusion of hydrogen into helium