Bohr model

[Image:Bohr-atom-PAR.svg|thumb|right|310px|The Rutherford–Bohr model of the hydrogen atom  or a hydrogen-like ion , where the negatively charged electron confined to an atomic shell encircles a small, positively charged atomic nucleus and where an electron jump between orbits is accompanied by an emitted or absorbed amount of electromagnetic energy (hν). The orbits in which the electron may travel are shown as grey circles; their radius increases as n², where n is the principal quantum number. The transition depicted here produces the first line of the Balmer series, and for hydrogen it results in a photon of wavelength 656 nm (red light).]]