NIELS BOHR Born: 7 Oct 1885 in Copenhagen, Denmark Died: 18 Nov 1962 in Copenhagen, Denmark Bohr expanded on Ernest Rutherford's theory, suggesting that electrons only travel in successively larger orbits and that the outer orbits hold more electrons than the inner ones. He also proposed that the outer orbits determined the atom's chemical properties and that atoms emit radiation when an electron jumps from an outer orbit to an inner one, emitting light.