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384
Aristotle
He did not accept Demarcates hypothesis he said everything was made of water, soil, pants, and fire. -
Dalton
Although two centuries old, Dalton's atomic theory remains valid in modern chemical thought. 1) All matter is made of atoms. Atoms are indivisible and indestructible. 3) Compounds are formed by a combination of two or more different kinds of atoms. -
Thompson
Development of the Atomic Theory. In 1897, J.J. Thomson discovered the electron by experimenting with a Crookes, or cathode ray, tube. He demonstrated that cathode rays were negatively charged. -
Rutherford-Gold foil Exp
Rutherford overturned Thomson's model in 1911 with his well-known gold foil experiment in which he demonstrated that the atom has a tiny, heavy nucleus. Rutherford designed an experiment to use the alpha particles emitted by a radioactive element as probes to the unseen world of atomic structure. -
Bohr
In atomic physics, the Rutherford–Bohr model or Bohr model, introduced by Niels Bohr and Ernest Rutherford in 1913, depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar in structure to the solar system, but with attraction provided by ... -
Heisenberg
In conclusion, Werner Heisenberg contributed to the atomic theory by including quantum mechanics, the branch of mechanics, based on quantum theory, used for interpretating the behavior of elementary particles and atoms. -
Democritus
Hypothesized that everything made of small items called atmos.