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442 BCE
Democritus
Democritus came up with the idea that matter was made up of invisible particles called atoms. -
350 BCE
Aristotle
Aristotle believed that all matter wasn't made up of atoms, but of the four elements, earth, wind, water, and fire. -
Evanglista Torricelli
Stated that atoms were specific to the thing they came from. -
Antoine Lavoisier
Stated that matter could not be created or destroyed. -
John Dalton
Proposed a new atomic theory using spherical solid. -
J.J. Thomson
Suggested model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces. -
Ernest Rutherford
Stated that the atom has a tiny, heated nucleus using the gold foil experiment. -
Robert Millikan
Discovered how to measure the charge of an electron. -
Niehls Bohr
Discovered that electrons travel in separate orbits around the nucleus. -
Werner Heisenburg
Found out that electrons don't travel in neat orbits, and included quantum physics in the atomic theory. -
Erwin Schrodinger
Used mathematical equations to describe the likelihood of finding an electron in a certain position. -
James Chadwick
Discovered neutrons in the atom.