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490 BCE
Democritus
The universe and all matter obey the following principles: Everything is composed “ atoms” which are physically, but not geometrically, indivisible . -
Antoine Lavoisier
Study of the burning process, he proposed the Combustion Theory which was based on sound mass measurements. -
Joseph Louis Proust
Best known for his discovery of the law constant composition. -
John Dalton
That all matter is made of Atoms. -
Airtotle
He thought that all materials on Earth were not made of atoms, but of the four elements, Earth, Fire, Water, and Air -
Michael Faraday
main discoveries include those of electromagnetic induction, diamagnetism and electrolysis. -
Henri Becquerel
Discovered Radioactivity. -
J. J. Thomson
Discovered the electron by experimenting with a Crookes, or cathode ray, tube. -
Marie & Pierre Curie
Discover Radium and Polonium -
Max Planck
German theoretical physicist who originated quantum theory. -
Albert Einstein
For the theory of relativity, which laid the basis for the release of atomic energy -
Ernest Rutherford
Well known gold foil experiment in which he demonstrates that the atom has a tiny, heavy nucleus. -
Niels Bohr
Hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. -
Robert Millikan
The measurement of the elementary electronic charge and for his work on the photoelectric effect -
James Chadwick
Bombarded beryllium atoms with alpha particles.