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Thales of Miletus 600 B.C.
-He thought everything was made from something else -
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Aristotle 384-322 B.C.
-He did not believe in the atomic theory, he agreed that everything was made up of Earth, wind, water, and fire. -
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Democritis 460-370 B.C.
-He though everything was held together by atoms.
-Democritis also thought that there was atom (came up with the term atom) -
Sir Isacc Newton
-Same thoughts as Democritis, also all particles move and are not stationary. -
John Dalton
-He discovered the atomic theory.
5 main points of Atomic Theory
1. Elements are made of extremely small particles called atoms.
2. Atoms of a given elemet are identical in size, mass, and other properties.
3. Atoms cannot be subdivided, created, or destroyed.
4. Atoms of different elements combine in simple whole-number ratios to form chemical compounds.
5. In chemical reactions, atoms are combined... -
Antoine Henri Becquerel
-He discovered the radioactivity in the atom
-performed the Uranium Experiment -
J.J. Thomson
-He discovered the electron through the Cathode Rays tube. -
Ernest Rutherford
-He discovered that atoms contain a nucleus surrounded by electrons through the Gold Foil Experiment. -
Robert Millikan
-He determined the charge and mass of an electron through the Oil Drop Experiment. -
Bohr
-Created the Bohr Model; said electrons are on fixed paths. -
Francis Aston
-He discovered isotopes. -
Schrodinger
-He used math equations to describe the probability of where an electron will be through the Quantum Model. -
James Chadwick
-He discovered evidence towards the existance of neutrons.