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430
Democritus - 430 BC
First proposed of the idea of the atom
Atom: a substance made up of tiny indestructible invisible particles
He started the continuing study on atoms and its characteristics -
Period: 430 to
Atomic Theory
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John Darlton- 1803
Proposed the atom is spherical solid atoms based upon measurable properties of mass. -
Michael Faraday- 1830's
In the 1830's, Michael Faraday, a British physicist, made one of the most significant discoveries that led to the idea that atoms had an electrical component. -
JJ Thomson- 1897
J.J. Thomson discovered the electron by experimenting with a Crookes, or cathode ray, tube. He demonstrated that cathode rays were negatively charged. -
Niels Bohr - 1913
In 1913 Bohr proposed his shell model of the atom to explain how electrons can have stable orbits around the nucleus. -
James Chadwick- 1932
James Chadwick discovered neutrons, particles whose mass was close to that of a proton.
