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200
Democritis
Beleived that if you continually cut a substance in half, eventually you would get an "uncuttable" piece. He called these uncuttable pieces particles, which means indivisible in greek. -
john dalton
e claimed the reason elements combined was because all elements are made up of atoms. He also published a three- part atomic theory. -
sir joseph john thomson (j.j thomson
Thomson used a cathode ray tube to inferr that there are small particles inside of every atom. -
neils bohr
This man suggested that electrons travel around the nucleus in definite paths. These paths are always at a certain "level" away from the nucleus. -
james chadwick
he discovered the exsistance of neutrons and that they had no charge at all,this ment that there was no eletical barrar to go through when trying to archive atom disginergration