The Bohr Model of Atomic Structure

The Bohr model allows only certain orbits with only certain energies, so an electron in an allowed state radiates nothing and a transition is a jump between two states rather than a drift through the space between them. For hydrogen the radius grows as $r_n = n^2 \times 0.053$ nm while the energy is $E_n = -13.6/n^2$ eV, so higher levels sit farther out and more weakly bound, crowding toward zero as $n$ climbs. The quantization follows from requiring the electron's de Broglie wave to close on itself, $n\lambda = 2\pi r$, working alongside the condition that the electric force supplies the centripetal force.

Three errors dominate. Running the planetary picture past the point the model supports, so the electron takes any radius or spirals between levels radiating continuously. Interchanging the $n^2$ dependence of the radius with the $1/n^2$ dependence of the energy, which inverts every downstream comparison. And missing that an allowed orbit is one whose circumference holds a whole number of de Broglie wavelengths, which leaves quantization as an unexplained assertion and gives the atom no reason to have a lowest state.