Electrons orbit the nucleus in fixed circular orbits with quantized angular momentum and absorb or emit energy when jumping between them.
Practise Atomic Structure & Periodicity All Atomic Structure & Periodicity topics
In 1913 Niels Bohr proposed that electrons orbit the nucleus only in certain circular orbits, in which the angular momentum is quantized as n h / 2 pi. While in these orbits electrons do not radiate energy, which resolved the collapse problem of the nuclear model. An electron emits or absorbs a photon when it jumps between orbits, with photon energy equal to the difference between the orbital energies. The model gives excellent results for hydrogen and for hydrogen-like one-electron ions such as He+. It was an essential bridge between classical and quantum physics.
Key ideas: Bohr (1913) postulated stationary circular orbits with angular momentum m v r = n h / (2 pi), no radiation in an orbit, and emission or absorption only for jumps with delta E = h nu. It correctly gives the hydrogen radius r = 0.529 n^2 / Z angstrom and energies, and explains line spectra.
Common mistakes and connections: Students think the electron physically jumps through space between orbits and treat orbits as real paths. Another error is that the model applies to many-electron atoms; it works only for hydrogen-like species. Its success is the quantization of angular momentum, and it was replaced by quantum mechanics.
Bohr placed hydrogen's single electron in a fixed circular orbit around the proton, with only certain allowed orbit radii. The interactive lesson shows this as a live animation or chart.
In He+ the orbital energies scale as Z squared times those of hydrogen, so the He+ levels lie four times deeper.
Electrons orbit the nucleus in fixed circular orbits with quantized angular momentum and absorb or emit energy when jumping between them.
Bohr Model is a intermediate topic in Atomic Structure & Periodicity. It builds on the vocabulary of beginner topics in this area.
Study these earlier topics in Atomic Structure & Periodicity first: Atomic Absorption Spectra, Hydrogen Spectrum Series, Rydberg Equation.
The next topics in Atomic Structure & Periodicity are Bohr Energy Levels and Limitations of Bohr Model.
Yes. The interactive lesson includes a self-check question on Bohr Model, and the Atomic Structure & Periodicity quiz draws on every topic in this area.
Bohr Model is topic 45 of 115 in Atomic Structure & Periodicity.