Visualize hydrogen atom emission spectra and energy level diagrams.
The hydrogen atom's emission spectrum was the experimental result that forced physicists to abandon classical mechanics and accept quantized energy levels — a foundational story in AP Chemistry Unit 1 and a frequent IChO atomic structure topic.
When an electron in a hydrogen atom drops from a higher energy level ni to a lower one nf, it emits a photon with energy exactly equal to the difference between those two quantized levels. The Rydberg formula, 1/λ = R∞(1/nf² - 1/ni²), where R∞ = 1.097 × 10^7 m⁻¹, predicts the exact wavelength of every possible transition — and every wavelength predicted by this simple formula has been experimentally confirmed to extraordinary precision.
Transitions are grouped into series by their final energy level. The Lyman series (transitions ending at n=1) falls entirely in the ultraviolet, since these are the largest possible energy gaps. The Balmer series (transitions ending at n=2) is the only series with lines in the visible spectrum — the four famous hydrogen emission lines at 656 nm (red), 486 nm (cyan), 434 nm (blue), and 410 nm (violet) all belong to this series and were the first spectral lines ever measured precisely, decades before quantum theory existed to explain them. The Paschen (n=3) and Brackett (n=4) series fall in the infrared.
Because energy levels get closer together as n increases (En = -13.6 eV/n²), transitions from very high n converge toward a series limit — the ionization energy for that series' final state. Photon energy, frequency, and wavelength are related by E = hν = hc/λ, letting any one property be calculated from another. Absorption spectra show the reverse process: an atom absorbing exactly the photon energies needed to promote electrons upward, producing dark lines at the same wavelengths as the corresponding emission lines.
This atomic spectra simulator lets you select any electron transition, instantly see the resulting photon's wavelength, frequency, and energy, and visualize which series and region of the electromagnetic spectrum it falls into — turning the abstract Rydberg formula into an interactive, visual tool.