... Energy Levels . ... Examining the Balmer formula and also the Ritz combination principle (further below), Bohr suggested that atoms could exist (even briefly) only in certain energy levels , and light was emitted only when an atom descended from some higher energy level to a lower one. ... When an electron descends from a higher energy (large n) to a lower one (smaller n), by Balmer's formula together with Einstein's, the energy of the photon emitted was exactly the amount of energy given up: . ...