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460 BCE
Democritus
by convention bitter, by convention sweet, but in reality atoms and void -
John Dalton
Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass. -
Marie Curie
Marie Curie theorized that radioactive particles cause atoms to break down, then releasing radiation that takes the form of energy and subatomic particles. -
J. J. Thomson
JJ Thomson discovers the electron, using properties of cathode rays. -
Max Planck
Max Planck introduced what would be known as quantum theory, stating that electromagnetic energy could only be emitted in quantized form. His quanta are now called photons by physicists. -
Albert Einstein
Albert Einstein, creates special and general theories of relativity, and hypothesizes about the particle nature of light. This was the basis of nuclear energy. -
Robert Millikan
Robert Millikan measured the charge of a single electron. This is known as the elementary charge, one of the fundamental physical constants. -
Ernest Rutherford
Ernest Rutherford known as the father of nuclear physics, developed the theory for the structure of the atom. He used a gold foil experiment, observing the scattering of alpha particles, and demonstrated for the first time the existence of the atomic nucleus. -
Neils Bohr
Neils Bohr developed the Bohr atomic model, with electrons travelling in orbits around the nucleus, and chemical properties being determined by how many electrons are in the outer orbits. He also integrated the Planck quantum theory, stating that when electrons change orbits they emit a quantum of discrete energy. -
Erwin Shrodinger
Erwin Shrodinger described how electrons move in wave form, and developed the Schrodinger equation which describes how the quantum state of a system changes with time. -
James Chadwick
James Chadwick discovers the neutron component of the atomic nucleus, explaining the nuclear fission of uranium 235. This also made it possible to produce elements heavier than uranium in the lab.
