jan 1, 1912 - 1912- Niels Bohr
Niels Bohr proposed the theory that energy is transferred in only in certain well defined quantities. He theorized that electrons rotated around the atom but it was a uniform way. In 1913 he theorized that energy is transferred in certain quantities. His theory explained why atoms emitted light in fixed wavelengths.
Added to timeline:
History of the Atom
by Katya Sander, Aurielle Smith, Amaya Mix