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Physics HL

Chapter 21: Atomic Physics

Build a full Chapter 21 pathway from Rutherford scattering evidence to quantised atomic energy levels, spectral transitions, and the Bohr model's angular-momentum postulate.

Estimated chapter time: 206 minutes

Chapter Topics

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  1. 1How to Read This Atomic Physics Chapter
    1. 1.1Why Atomic Physics Changed the Structure of Matter
    2. 1.2Learning Targets
    3. 1.3Recommended Problem-Solving Workflow
  2. 221.1 The Structure of the Atom
    1. 2.1Geiger-Marsden-Rutherford Experimental Logic
    2. 2.2Why Large-Angle Events Require a Tiny Nucleus
    3. 2.3Scale Separation: Atom Radius Versus Nucleus Radius
  3. 321.2 Discrete Energy Levels and Emission Spectra
    1. 3.1Discrete Energy as the Signature of Atomic States
    2. 3.2Hydrogen Energy Formula and Transition Energetics
    3. 3.3Series Structure and Why Lines Cluster
  4. 421.3 Absorption Spectra and Excitation Pathways
    1. 4.1Why Absorption Lines Match Emission Lines
    2. 4.2Photon Excitation Versus Electron Impact
    3. 4.3Spectral Fingerprints and Astrophysical Inference
  5. 521.4 Quantisation of Angular Momentum in the Bohr Model
    1. 5.1The Classical Stability Problem
    2. 5.2Bohr Postulate and Allowed Angular Momentum
    3. 5.3Allowed Radius and Energy Relations
  6. 621.5 Bohr Predictions, Series Limits, and Model Boundaries
    1. 6.1Spectral Series and Convergence Limits
    2. 6.2Ionisation Energy and Bound-State Meaning
    3. 6.3What Bohr Gets Right and What It Misses
  7. 7Chapter 21 Wrap-Up
    1. 7.1One Workflow for Atomic-Structure Questions

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