Bohr's model of the atom arranges electrons in well defined fixed orbitals around the nucleus similar to planets orbiting the sun. Electron movement between orbitals results in atomic spectrums.
Electrons can be exited to the point of jumping to another orbital level and will absorb or emit energy in the form of photons that is exactly equal to the energy required to make the jump.
Each atom has a characteristic color spectrum associated with it that can be viewed when energy is added to the element. The energy addition may be rapid oxidation (burning) or electrical current passing through a gas.
You will have witnessed the colors visible from electron energy jumps by watching fireworks, neon lights, or colored LED's, including white LED's.
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