A Level Nuclear Physics Hub
A Level Nuclear Physics hub covering nuclear structure, radioactive decay, beta decay, mass–energy, binding energy, fission, fusion and radiation hazards.
Learning goals
- Interpret nuclear structure, isotopes and Rutherford scattering.
- Analyse random radioactive decay, activity, decay constant and half-life.
- Relate binding energy per nucleon to fission, fusion, applications and hazards.
- Apply conservation laws to nuclear equations and beta decay, including antineutrino evidence.
- Use mass-energy equivalence, mass defect and binding energy.
Nuclear Physics connects evidence about the nucleus to two quantitative models: random radioactive decay for populations and mass–energy accounting for bound systems and reactions.
Prerequisites: O-Level Radioactivity, Quantum Physics, conservation laws, exponential functions and graph gradients.
Route: scattering evidence and nuclear structure → random decay and beta decay → mass–energy and binding → fission, fusion, uses and hazards.
After this hub: take the Nuclear Physics Quiz, then complete the Nuclear Physics Structured Set.
Lessons
Work through these lessons in order.
- Nuclear structure and nuclides
- Random decay, radiation, activity and half-life
- Applications and hazards
- Nuclear equations, conservation and beta decay
- Mass defect and binding energy
- Binding energy in fusion and fission
- The Alpha-particle Scattering Experiment
Use the Rutherford alpha-particle scattering results to infer the nuclear atom: tiny, massive, positively charged nucleus and mostly empty space (A Level Physics).
- Simple Model Of The Atom
Describe the nuclear atom model, define proton number Z and nucleon number A, and use nuclide notation for isotopes (A Level Physics).
- Atomic Mass
Define the unified atomic mass unit u, convert between u and kg, and use atomic masses in nuclear calculations (A Level Physics).
- Random Nature of Radioactive Decay (Count Rate & Background Radiation)
Explain why radioactive decay is random, interpret fluctuating count-rate data, and correct measurements for background radiation (A Level Physics).
- Activity, Half-life and Decay constant
Define activity, decay constant and half-life, and solve problems using A=λN, N=N0 e^{-λt}, and t1/2 = ln2/λ (A Level Physics).
- Nuclear Reactions
Write balanced nuclear equations and apply conservation of nucleon number, charge, and mass–energy to nuclear processes (A Level Physics).
- Neutrino In Beta Decay (Conservation of Energy & Momentum)
Explain why beta particles have a continuous range of kinetic energies and how the antineutrino preserves energy and momentum in beta-minus decay.
- Mass-energy Relation
Use E = mc^2 to link mass defect to energy release in nuclear reactions, and write exam-ready explanations of mass–energy conservation (A Level Physics).
- The Mass Defect
Define mass defect and calculate Δm using nuclear or atomic masses; connect mass defect to binding energy via ΔE = Δm c^2 (A Level Physics).
- Binding Energy
Define nuclear binding energy, relate it to mass defect using E_b = Δm c^2, and use it to compare nuclear stability (A Level Physics).
- Binding Energy Per Nucleon And Nuclear Stability
Interpret the binding energy per nucleon curve, identify stable nuclei near iron, and relate the curve to energy release in fusion and fission (A Level Physics).
- Nuclear Fission
Explain nuclear fission and why it releases energy using the binding energy per nucleon curve; write nuclear equations and common exam explanations (A Level Physics).
- Nuclear Fusion
Explain nuclear fusion and why it releases energy for light nuclei using the binding energy per nucleon curve; describe the Coulomb barrier and conditions needed (A Level Physics).
- Effects of Radiation on Living Organism
Discuss hazards and applications of radioactivity using half-life, penetration, and ionisation: compare alpha, beta, and gamma and choose suitable shielding (A Level Physics).
- Geiger-Muller Tube/Counter · Supporting
Understand how a Geiger–Müller tube detects ionising radiation and why it produces count-rate data with dead time and quenching (optional enrichment for A Level Physics).
- Safety Precautions Around Radioactive Sources · Supporting
Supplementary radioactive-source safety covering time, distance, suitable shielding, contamination control, monitoring and authorised disposal.
Revision
Scattering evidence checkpoint
Write scattering explanations as observation → inference. Do not claim that every alpha particle passes close to the nucleus; large deflections are rare because the nucleus occupies a tiny fraction of the atom.
Radioactive decay checkpoint
| Quantity | Relationship | Interpretation |
|---|---|---|
| Number undecayed | N = N₀e^(-λ t) | expected population, not a schedule for one nucleus |
| Activity | A = λ N = -dN/dt | source decays per second; unit Bq |
| Half-life | t_(1/2) = ln 2/λ | same time unit as 1/λ |
| Net count rate | measured rate − background rate | detector result, not total source activity |
Mass–energy method
- State whether the supplied values are atomic masses or nuclear masses; do not mix the two methods.
- Find the mass difference using one consistent set of constituents.
- Use E = Δ mc² in SI, or 1 u c² = 931.5 MeV when working in atomic mass units.
- For a reaction, Q = (m_reactants-m_products)c²; positive Q means energy is released.
- For stability comparisons, calculate binding energy per nucleon, not merely total binding energy.
Binding-energy curve checkpoint
“Mass is lost” is incomplete. State that the products have greater total binding energy and lower total rest mass, so the mass–energy difference appears mainly as kinetic energy and radiation.
Exam traps
- Half-life is statistical. It does not predict when a named nucleus will decay.
- Activity and count rate differ. Detector geometry and efficiency mean a detector normally records only a fraction of all decays.
- Background is subtracted before analysis. Otherwise late-time half-life estimates are biased.
- Atomic and nuclear masses require different bookkeeping. Electron masses must cancel consistently.
- Mass defect is not missing matter. It is the lower mass–energy of the bound system.
- Greater total binding energy does not automatically mean greater stability. Compare binding energy per nucleon.
- A beta spectrum is continuous. The electron, antineutrino and daughter recoil share the available energy.
Practice
Use the quiz to identify a weak outcome, then complete one decay-data question and one mass–energy question under timed conditions.
End of the A-Level topic sequence. Return to the A-Level Physics Portal.
Continue with the next resource in this course.
Course and syllabus information
- Course
- GCE A-Level H2 Physics
- Edition
- GCE A-Level H2 Physics 2027