Bohr Atom Simulator
How to use the Bohr atom simulator
- The electron circles the nucleus on one of the allowed orbits, numbered n = 1 (closest) to 7. Choose a start level and a lower end level.
- Click Emit photon: the electron drops to the lower orbit and a photon flies off, coloured by its wavelength (white for ultraviolet, dark red for infrared).
- Read the energy of each level, the photon energy and its wavelength and series.
Frequently asked questions
What is the Bohr model?
Niels Bohr's 1913 picture of the hydrogen atom: the electron can only occupy orbits with energies E = −13.6 eV ÷ n², and it jumps between them by emitting or absorbing a photon whose energy is the difference. It explains the hydrogen spectrum exactly, though quantum mechanics has since replaced the orbits with orbitals.
How is the wavelength worked out?
The photon energy is the difference between the levels, ΔE = 13.6 eV × (1 ÷ nf² − 1 ÷ ni²), and the wavelength is λ = hc ÷ ΔE = 1,240 eV·nm ÷ ΔE. For the 3 → 2 jump that is 1.89 eV and 656 nm, the red H-alpha line.
What are the Lyman, Balmer and Paschen series?
Families of spectral lines named by the level the electron lands on: Lyman ends on n = 1 and is in the ultraviolet, Balmer ends on n = 2 and includes the four visible hydrogen lines (656, 486, 434 and 410 nm), and Paschen ends on n = 3 in the infrared.
It says WebGL is turned off.
The 3D view needs WebGL, which every current browser has. It can be switched off by hardware acceleration being disabled in the browser settings, or by a very old graphics driver. Turn hardware acceleration on, or try another browser.
Is anything uploaded?
No. The simulation is drawn by your own browser with WebGL; nothing is sent anywhere, and it keeps working offline once the page has loaded.