Millikan measured the charge of an electron with his Oil Drop Experiment. He proved the existence of the electron and stated that 1.6 * 10^-19 C was the charge of an electron. After this, he concluded that the atom was built of smaller particles and was not a fundamental particle. Millikan’s findings of the electron having a negative charge was correct.
But he was incorrect when he explained his experiment’s results as a lesser value instead of the current value for the charge of an electron.Bohr published the Bohr model, which his model of atomic structure. This model shows the atom as a positively-charged nucleus. That’s surrounded by negative charged electrons traveling in circular orbits around the nucleus.
Bohr compares its structure to the solar system, but with electromagnetic forces that provide attraction and not gravity. He also said that electrons travel in separate orbits around the atom’s nucleus, which is the chemical properties of the element being processed by the number of electrons found in outer orbits. Another thing, an electron could change from a higher energy orbit to a lower one, producing a particle of separate energy.