Atomic Emission Spectrum Simulator

Bohr Atom

Excite to level n = 4

Animation speed 1.0×

Electron shell

n = 1

Photons emitted

Last transition

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Photon energy

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Wavelength

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Spectral band

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Emission spectrum

How it works

In the Bohr model, a hydrogen electron can only occupy discrete energy shells n = 1, 2, 3…, each with energy Eₙ = −13.6 eV / n². Absorbing a photon of exactly the right energy kicks the electron up to a higher shell; left alone, it falls back down, level by level, releasing the energy difference as a single photon at each step. The photon's color is set entirely by that energy gap.

E(n) = −13.6 eV / n²
ΔE = E(n_low) − E(n_high)
λ = 1239.84 eV·nm / ΔE

Excite to level — the shell the electron jumps to when you fire an absorption photon into the atom.
Excite electron — sends a photon in from outside; on arrival the electron jumps straight to the chosen shell, then begins its cascade.
Auto mode — keeps re-exciting the atom to a random shell whenever it settles back to the ground state, so the spectrum strip fills up on its own.
Animation speed — scales both the orbital motion and how quickly each cascade step fires.

Real-world relevance: this cascade is exactly what produces atomic emission lines — the Balmer series (visible light, transitions ending at n = 2) is what makes hydrogen glow pink-violet in a discharge tube, while the Lyman series (ending at n = 1) is invisible ultraviolet. Spectroscopes and lasers both exploit these same fixed energy gaps.

Nucleus (proton) Electron Absorbed photon Emitted photon

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