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450
Democritus's Atomic Theroy (460)
Democritus contemplated that everything is made of atoms, and he discovered atoms are physically, but not geometrically, indivisible; between atoms lies empty space; atoms are indestructible. He came to this conclusion by taking a seashell and breaking it in half and reapeating this until it was a fine powder and he could no longer break it down. Citation:"Democritus Atom." Universe Today RSS. N.p., n.d. Web. 23 Feb. 2014. -
450
Aristotle's Atomic Theroy (400)
Aristotle didn't agree with Democritus's theroy about atoms so instead, he created his own theroy about matter. He believed that matter was made of the four elements, earth, fire, wind, and air. He also had no proof about this but because he was liked people belived it. -
John Dalton's Atomic Theroy
John Dalton developed the Atomic Theory in 1800. He still believed that the atom was the smallest unit of matter, and that it could not be bvroken down. He believed in Democritus' theory of the atom looking like a marble. John Dalton also tried to calculate the atomic weight of compounds. He also tried to come up with the atomic stuructures of atoms. His evidence was the first volume of the New Systems of Chemical Phiosophy -
J.J. Thomson's Atomic Theroy
Thomson used a cathode ray tube to inferr that there are small particles inside of every atom. Through this expirement thomson also inferred that atoms must be negatively charged.Thomson purposed the plum pudding model which allowed scientefic advances to occur. -
Ernest Rutherford's Atomic Theroy
He thought if the particles were soft as J.J. Thomson's plum pudding model had suggested than they would pass Through and continue in a straight line, Which most did. However some did not this showed that the plum pudding model was somewhat false, so rutherford created a new model. In his Gold Foil Model Rutherford shot a positively charged beam of particles through a sheet of gold foil. -
Niels Bohr's Atomic Theroy
This man suggested that electrons travel around the nucleus in definite paths. These paths are always at a certain "level" away from the nucleus. He also stated that electrons cannot travel in between each path, however they can jump from one path to another. -
Heisenberg and Schrodinger's Atomic Theroy
Austrian physicist Erwin Schrodinger formed a model of a complete atom as interacting waves. The particles became like vibrations on a violin string, only they were closed in circles. German physicist Werner Heisenberg formulated his uncertainty principle which says that you cannot know by measurement the position and momentum of a particle simultaneously. He also thought atoms were now visualized as a nucleus surrounded by a cloud of electrons distributed according to a wave pattern.
