Hydrogen spectrum

The hydrogen spectrum is the set of discrete wavelengths emitted or absorbed when hydrogen’s electron changes energy levels. Its line pattern reflects the atom’s quantized energy states.

Bohr model: An atomic model in which electrons occupy quantized orbits and emit or absorb light when changing orbits. It first accounted for hydrogen’s spectral lines by assigning discrete energies to its electron.
Hydrogen atom: The simplest atom, consisting of one proton and one electron, with isotopes containing additional neutrons. Its single-electron structure makes the origin of the spectrum unusually tractable.
Lyman series: Hydrogen spectral lines produced by transitions ending at the ground state, in the ultraviolet. These transitions form hydrogen’s ultraviolet series.
Johann Balmer: A Swiss mathematician who found a formula for the visible lines of hydrogen in 1885. His empirical relation described the visible subset later named the Balmer series.
Stellar spectroscopy: The analysis of starlight spectra to infer stars’ composition, motion, and physical conditions. Hydrogen lines help identify stellar atmospheres and measure their temperatures and velocities.
Rydberg formula: A formula that predicts the wavelengths of spectral lines in hydrogen and hydrogen-like atoms. It calculates line positions from integer level numbers without modeling each transition’s details.
Atomic spectrum: The pattern of wavelengths emitted or absorbed by atoms through transitions between their energy states. Hydrogen’s lines are a particularly simple example of atomic spectra.
Balmer series: Hydrogen spectral lines produced by transitions ending at the second energy level, including visible lines. Its prominent visible lines made hydrogen’s pattern accessible to early spectroscopy.
Johannes Rydberg: A Swedish physicist who developed a formula organizing the spectral lines of many elements. His formula generalized the regularity evident in hydrogen’s line wavelengths.
H II region: A region of ionized hydrogen surrounding hot stars that emit ultraviolet radiation. Recombining hydrogen produces characteristic emission lines in these nebulae.

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