plum pudding model

His earliest major success was the accurate determination of the charge carried by an electron, using the elegant “falling-drop method”; he also proved that this quantity was a constant for all electrons (1910), thus demonstrating the atomic structure of electricity.

Robert Millikan was able to determine the mass of an electron by using charged oil drops. Electrons have such a small mass, they were believed to be massless. Millikan’s experiment determined that the electrons did, indeed, have mass. I hope this helps.

Millikan discovered that there is a fundamental electric charge—the charge of an electron. Rutherford’s gold foil experiment showed that atoms have a small, dense, positively charged nucleus; the positively charged particles within the nucleus are called protons.

In 1909, Millikan performed his famous oil drop experiment and determined the charge ( e ) of the electron. The gold foil experiment was performed in 1909. It wasn’t until 1911 that Rutherford wrote his paper proposing the nuclear model of the atom. So Millikan’s oil drop experiment didn’t change the model of the atom.

In the Bohr model of the atom, electrons travel in defined circular orbits around the nucleus. The orbits are labeled by an integer, the quantum number n. Electrons can jump from one orbit to another by emitting or absorbing energy.

Rutherford proposed that electrons circled the nucleus like planets around the sun. However, his model could not explain atomic line spectra — why metals or their compounds give off characteristic colours when heated.