jan 1, 1913 - Neils Bohr developed a new atomic model.
Rutherford’s model was helpful in discovering the nucleus, but it could not explain the chemical properties of elements. Bohr proposed that an electron is found only in specific orbits around the nucleus and they all had a fixed energy called energy levels. His model was a step in the right direction to describing the chemical properties of elements, which had to do with energy, but he was still missing a piece. Scientists later on used his model to discover and learn more about the chemical properties of elements.
Added to timeline:
The Atom vs the Telephone