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450 BCE
Democritus
Democritus thought about what happens when you cut the smallest matter into a smaller piece, in about 450 B.C. -
Isaac Newton
Isaac Newton theorized a mechanical universe with small, solid masses in motion. -
Dalton
Around 1800, a British chemist named John Dalton revived Democritus’s early ideas about the atom. -
Mendeleev
Dmitri Mendeleev created the periodic table. -
Wilhelm Roentgen
Wilhelm Roentgen discovered x-rays. -
Thomson
Thomson discovered electrons. -
Cathode Ray Tube Expirement
The first ray tube was invented by William Crookes in 1897. The development of the television was based on the CRT. -
Rutherford
Rutherford discovered the nucleus. -
Max Planck
Max Planck proposed the idea of quantization to explain how a hot, glowing object emitted light. -
Millikan Oil Drop Experiment
Robert A Millikan created a way to measure the electric charge of a single electron, using the oil drop experiment. -
Gold Foil Experiment
In 1911, Rutherford used alpha particles to study atoms. He aimed a beam of alpha particles at a very thin sheet of gold foil. -
Bohr
In 1913, Niels Bohr proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. -
Francis William
Francis William Aston used a mass spectrograph to identify 212 isotopes. -
Electron Cloud Model
Erwin Schrödinger developed the probability function for the Hydrogen atom. The cloud model represents a sort of history of where the electron has probably been and where it is likely to be going. -
First Nuclear Reactor
Enrico Fermi created the first man-made nuclear reactor.