Nuclear physics: decay, reactions and binding
Key idea: Separate random single-nucleus behaviour from population laws, conserve every required quantity in reactions, and explain released energy through increased binding rather than disappearing mass.
Before you start: Quantum Physics objective chainMeasurement objective chain
By the end, you can
- Interpret nuclear structure, nuclides, random decay and radiation measurements.
- Evaluate radioisotope applications and hazards from physical properties.
- Balance nuclear reactions and use conservation to explain antineutrino evidence.
- Connect mass defect, binding energy and the binding-energy curve to fusion and fission.
Starting-point self-check
1. Check your starting point
Attempt all six groups without notes and mark the first structure, decay, risk, conservation, binding or curve decision you cannot justify. Use the recorded topic diagnostic above when you want scoring and a personalised repair plan.
Binding energy in fusion and fission 20(t)
Question 1
Explain why both light-nucleus fusion and heavy-nucleus fission can release energy.
Check the model response
Products move toward greater binding energy per nucleon, reducing total mass-energy and releasing the difference.
repair
2. Repair the common breaks
Use only the correction matching an error, then retry the corresponding diagnostic.
Binding energy in fusion and fission 20(t)
Check this idea
Misconception: Fusion and fission release energy for opposite unrelated reasons.
Repair: Both can move products toward higher binding energy per nucleon.
worked example
3. Follow six worked models
Follow how each solution uses evidence, corrected data, risk criteria, conservation or the binding-energy curve.
Binding energy in fusion and fission 20(t)
Model 1
Use the binding-energy-per-nucleon curve to compare deuterium fusion and uranium fission.
Check the model response
Light nuclei rise steeply toward the iron-region maximum when fused; very heavy nuclei move upward when split into medium nuclei. The increase in total binding energy is released.
guided practice
4. Guided practice
Use each hint only to select the correct nuclear number, population relation, radiation property or energy comparison.
Binding energy in fusion and fission 20(t)
Question 1
Products have higher binding energy per nucleon. State the energy sign.
Hint: More tightly bound means lower system energy.
Check the model response
Energy is released; the products have lower total mass-energy.
independent practice
5. Independent practice
Solve without repair notes and state background, conservation, exposure and curve assumptions.
Binding energy in fusion and fission 20(t)
Question 1
Explain fusion and fission using the curve rather than saying that mass disappears.
Check the model response
Both can move products toward the curve's higher binding-energy-per-nucleon region. Greater total binding lowers product mass-energy, and the difference appears as kinetic energy and radiation.
Practice exit check
6. Practice assessment
Use this as extra closed-book practice, then complete the separate recorded assessment in your plan.
Binding energy in fusion and fission 20(t)
Question 1
A reaction increases total binding energy by 3.2 MeV. State mass change and energy output.
Check the model response
Mass decreases by Δm = 3.2 MeV/c² and 3.2 MeV is released.
Re-test practice
7. Delayed re-test practice
Return after at least three days and solve these fresh contexts without reopening earlier responses. The recorded plan enforces the delay and uses a separate re-test family for selected-response skill-group evidence.
Binding energy in fusion and fission 20(t)
Question 1
What single curve feature permits energy release in both processes?
Check the model response
Both product sets can lie higher on the binding-energy-per-nucleon curve than their reactants.