Chemistry: Atomic Theory Scientists - Third Half

Ernest Rutherford

Discovered the atomic nucleus in 1911 through his famous Gold Foil Experiment, proving that atoms are mostly empty space with a dense, positively charged core, while also discovering alpha and beta particles and coining the term "half-life."

Robert Millikan

Determined the charge of an electron in 1909 using his Oil Drop Experiment, proving that electrical charge is quantized, and later verified Einstein’s photoelectric equation to measure Planck's constant.

Niels Bohr

Proposed the nucleus and emit or absorb light only when jumping between these energy levels.

James Chadwick

Discovered the neutron in 1932 by bombarding beryllium atoms with alpha particles, identifying a neutral subatomic particle in the nucleus with a mass similar to a proton, which ultimately paved the way for nuclear fission.