Hydrogen physics

A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 e (elementary charge). Its mass is slightly less than the mass of a neutron and approximately times the mass of an electron (the proton-to-electron mass ratio). Protons and neutrons, each with a mass of approximately one dalton, are jointly referred to as nucleons (particles present in atomic nuclei).

atomic model introduced by Niels Bohr in 1913

form of association between an electronegative atom and a hydrogen atom attached to a second, relatively electronegative atom

thumb|right|upright=1.2|Antihydrogen consists of an antiproton and a [[positron]] thumb|right|upright=1.2|Simplified model of an antihydrogen atom in ground state

atom of element hydrogen

phase of hydrogen

hydrogen spectral series

liquid state of the element hydrogen

important atomic emission spectra

formula for spectral line wavelengths in alkali metals

hydrogen spectral series of transitions

spectral line of hydrogen state transitions

atomic nucleus with one electron that behaves like hydrogen

thumb|In the Bohr model of the hydrogen atom, the electron transition from energy level n = 3 to n = 2 results in the emission of an H-alpha photon.

hydrogen atom that has gained or lost an electron

chemical compound

negative ion of hydrogen

molecular ion

hydrogen in a solid state

thumb|upright|The All-sky New Horizons Alice Lyα maps in ecliptic coordinates centered on the anti-Sun direction, and the lower map is in Galactic coordinates. The c. 90,000 stars in the M. A. Velez et al. (2024) catalog are overlaid as black dots, where the size of the dot is proportional to the logarithm of the expected Alice count rate from each star. The map in Galactic coordinates indicates the outlines of four of the important LISM clouds ("LIC", in red; "Aql" in green; "Blue", in blue; and "G", in tan). Lyman-alpha, typically denoted by Ly-α or Lyα, is a spectral line of hydrogen (

extension of the Bohr model to allow elliptical orbits of electrons around an atomic nucleus

gaseous state of the element hydrogen kept under pressure

difference of intensity of the stellar continuum spectrum

combination of liquid hydrogen and solid hydrogen

spin states of hydrogen

exotic atom consisting of a negatively charged kaon orbiting a proton