Bohr model

The CED is careful about what this model is (15.2.A.3): based on classical physics, and the historical representation of the atom that led to the description of the hydrogen atom in terms of discrete energy states.

Mechanically it is a circular-motion problem. 15.2.A.3.i puts the electron on a circle set by its own charge and mass and by the electric force between electron and nucleus, and cites two equations borrowed from elsewhere on the sheet rather than any of its own: $F_E = k \frac{|q_1 q_2|}{r^2}$ and $F_{\text{net}} = m \frac{v^2}{r}$. The Modern Physics group of the sheet contains nothing for this topic.

What makes the orbits discrete is 15.2.A.3.ii. The circumference of the electron's orbit must be a whole number of de Broglie wavelengths, so only certain radii, and therefore only certain energy levels, survive. That standing-wave condition is the model's success.

Its limits are set by the CED rather than argued. The Topic 15.2 boundary statement restricts the analysis and description of electron structure to energy levels and excludes orbitals, orbital shapes and probability functions. The Topic 15.3 boundary statement allows only energy level diagrams of single-electron atoms.

The value $E_n = (-13.6 \, \text{eV})/n^2$ appears once in the entire CED, inside an optional sample instructional activity, and on no equation sheet.