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.
Nuclear structure and nuclides 20(a)–(c)
Question 1
State what Rutherford scattering implies and interpret ²³₁₁Na.
Check the model response
Rare large deflections imply a very small positive nucleus; most particles passing through imply mostly empty space. Sodium-23 has 11 protons and 12 neutrons.
repair
2. Repair the common breaks
Use only the correction matching an error, then retry the corresponding diagnostic.
Nuclear structure and nuclides 20(a)–(c)
Check this idea
Misconception: Isotopes have different proton numbers.
Repair: Isotopes share proton number and differ in neutron number.
worked example
3. Follow six worked models
Follow how each solution uses evidence, corrected data, risk criteria, conservation or the binding-energy curve.
Nuclear structure and nuclides 20(a)–(c)
Model 1
Connect the frequency of Rutherford deflections to nuclear size and charge.
Check the model response
Most alpha particles see little concentrated charge; rare close approaches experience strong repulsion and large deflection. Rarity bounds the positive region to a tiny fraction of atomic volume.
guided practice
4. Guided practice
Use each hint only to select the correct nuclear number, population relation, radiation property or energy comparison.
Nuclear structure and nuclides 20(a)–(c)
Question 1
For ³⁷₁₇Cl, state proton and neutron numbers.
Hint: Neutrons equal A − Z.
Check the model response
17 protons and 20 neutrons.
independent practice
5. Independent practice
Solve without repair notes and state background, conservation, exposure and curve assumptions.
Nuclear structure and nuclides 20(a)–(c)
Question 1
Explain Rutherford evidence and distinguish nucleon number, proton number and isotopes.
Check the model response
Scattering supports a tiny positive nucleus and mostly empty atom. A counts protons plus neutrons; Z counts protons and identifies the element. Isotopes share Z but differ in neutron number and A.
Practice exit check
6. Practice assessment
Use this as extra closed-book practice, then complete the separate recorded assessment in your plan.
Nuclear structure and nuclides 20(a)–(c)
Question 1
An isotope is ⁶⁰₂₇Co. State its composition and the Rutherford observation supporting a small nucleus.
Check the model response
27 protons, 33 neutrons. Rare large-angle or backward alpha scattering supports a small concentrated nucleus.
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.
Nuclear structure and nuclides 20(a)–(c)
Question 1
What differs between isotopes of one element?
Check the model response
Neutron number and hence nucleon number; proton number is the same.