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100
Democritus
He wasthe first to suggest that matter could not be infinetly divided.
"Atoms can not be created, destroyed, or further divided."
(460-370 B.C.) -
110
Aristotle
He disagreed with Democritus' idea that atoms move through emptey space. He completely denied the exstence of atoms because of his personal beliefs. His ideas toke Democritus back to square one.
(384-322 B.C.) -
John Dalton
He marks the beginning of the development of modern atomic theory.
He took Democritus' ideas about matter and revised them based off the of his personal scientific research.
( 1776- 1844)
Dalton's atomic theory was widely accepted upon its ability to explain the conservation of mass. -
Sir William Crookes
He saw a green flash of light in a cathode tube and found the atom and found that atoms carry negative charges ( electrons ). -
Physicist J.J Thompson 1897
He designed a CRT experiment to determine the ratio of the particles charge to its mass. Also found out that mass of the particle was much less of the particle was much less than of the hydrogen atom which disproved Daltons theory that atoms were invincible. -
Physicist Robert Milikan
He determined magnitude of the charge of the electron was 1.602 x 10-9( exponential ) -
Ernest Rutherford
He came to the conclusion that Thompson's plum pudding model of the atom was incorrect. Also that a majority of the mass were they positive charges are. He studied how positive the particles interact with solid matter. His model shows the neutral nature of the matter with the balance of positive charge in the nucleus and a negative charge of electrons around it. He also said the nucleus included positive charges. -
James Chadwick
First person to demonstrate that the nucleus had a nutural subatomic particle. (Neutron)
