In 1913, Neils Bohr built on the work of Max Planck and Albert Einstein and proposed that the movement of electrons within an atom was quantized. In other words, Bohr’s work suggested that electrons do not move freely around the atom, but can only occupy specific energy levels within the atom. Evidence that led to this proposal was the observation of line spectra – distinct bands of light emitted by atoms after they were excited by heat or electricity. Bohr’s theory explained that those spectral emission lines were due to the energy released by the relaxation of excited electrons between specific orbitals. This animation allows you to add different amounts of energy to see how the electron in a hydrogen atom responds, and then manually allow that electron to relax to specific orbitals within the atom (note that in nature electrons relax spontaneously and instantaneously). The animation provides data on the energy added and released and the resulting wavelengths of light emitted. The complete line spectra for the transitions represented in this animation are shown below (note, a hydrogen atom has additional lines related to transitions not shown here).
For more information, see Visionlearning module Atomic Theory II.
Bohr’s Atom: Electron Transitions
in the Hydrogen Atom
Energy (Input, eV)
Neils Bohr proposed that electrons resided in specific orbitals within atoms in his groundbreaking work on atomic theory. Compare how inputting certain amounts of energy result in the emission of light with specific characteristics in this animation.