Learning Hub/Simulation Registry/Physics/HL/Chapter 21

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.

1 simulation entries

Simulation: Rutherford Scattering Comparator

Compare trajectory deflection trends for concentrated nuclear charge and diffuse Thomson-style charge while tuning impact parameter and alpha energy.

Appears in: 21.1 The Structure of the Atom, 21.2 Discrete Energy Levels and Emission Spectra, 21.3 Absorption Spectra and Excitation Pathways, 21.4 Quantisation of Angular Momentum in the Bohr Model, 21.5 Bohr Predictions, Series Limits, and Model Boundaries

Explore how atomic structure evidence, quantised levels, and spectral lines connect to one another.

Atom region (Thomson picture)nucleusthetacyan: Rutherford (nucleus concentrated)yellow: Thomson (charge spread out)

Rutherford deflection

13.35 deg

Thomson deflection

2.33e-7 deg

Head-on closest approach

42.13 fm

Large-angle rarity

~1 in 1,000,000

Model notes: Rutherford mode compares angular deflection scaling for concentrated vs spread positive charge; transitions and Bohr modes use hydrogen-like one-electron formulas; spectra mode emphasizes line-position matching between emission and absorption.