Chapter 21: Nuclear Physics

Effective Study Strategies

• Understand atomic structure evolution: Dalton → Thomson → Rutherford → Bohr → Quantum model. Know key experiments and discoveries.
• Master nuclear notation: $_{Z}^{A}X$ where A = mass number, Z = atomic number. For isotopes: same Z, different A.
• Differentiate between isotopes, isotones, isobars: Isotopes (same Z), isotones (same N), isobars (same A).
• Calculate mass defect and binding energy: Δm = (Z m_p + N m_n) – m_nucleus. B.E. = Δm × c².
• Understand radioactive decay types: α-decay (A↓4, Z↓2), β-decay (A same, Z↑1), γ-decay (no change in A or Z).
• Master half-life calculations: N = N₀(1/2)^(t/T). T = 0.693/λ.
• Know radiation properties: α (He nucleus, +2e, 4u), β (electron, -e, 0.00055u), γ (EM wave, no charge/mass).
• Understand nuclear reactions: Fission (heavy nucleus splits), fusion (light nuclei combine). Know examples and energy release.

Exam Preparation Tips

• Memorize key discoveries: Dalton (1808), Thomson (electron 1891), Rutherford (proton 1919, nuclear model 1913), Chadwick (neutron 1932).
• Practice nuclear equations: Balance mass and atomic numbers in decay equations.
• Calculate decay constant and activity: A = λN, T½ = 0.693/λ.
• Know radiation detectors: Wilson cloud chamber (tracks), Geiger-Muller counter (ionization), solid-state detector.
• Understand radiation safety: Units (Gray, Sievert), biological effects, safe exposure limits.
• Study particle physics basics: Quarks (up, down, strange, charm, bottom, top), leptons, hadrons.
• Practice unit conversions: 1 u = 1.6606×10⁻²⁷ kg, 1 Ci = 3.7×10¹⁰ Bq, 1 Gy = 1 J/kg.

Common Pitfalls to Avoid

• Confusing atomic number (Z) with mass number (A)
• Mixing up α, β, γ radiation properties and penetration powers
• Forgetting that γ-rays have no mass or charge (not particles)
• Not balancing nuclear equations (sum of A and Z must be equal on both sides)
• Confusing half-life with decay constant (T½ = 0.693/λ)
• Mixing up fission (splitting heavy nuclei) and fusion (combining light nuclei)
• Forgetting that binding energy per nucleon is maximum for iron (most stable)
• Confusing isotopes (same Z) with isobars (same A)