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500
Aristotle
Aristotle develops his theory stating that no matter how many times you divide matter there will always be a piece of matter that is smaller. -
500
Democritus
States that all matter is made up of tiny, invisible, indivisible particles called atoms. -
Period: 500 to
The History of The Atom
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James Dalton
Dalton formed the theory that all matter is composed of small particles called atoms. These atoms were said to all be the same -
Henri Becquerel
Henri Becquerel discovers some chemicals desintigrate with the effects of x-rays. He discovered radioactivity. -
Marie and Pierre Curie
The duo started experimenting with radioactive substances and discovered radium and polonium. -
J.J Thomson
Discovered the electron and put together the plum pudding model. -
Robert Millikan
Millikan discovered the electric charge in an electron. -
Ernest Rutherford
After Rutherfords gold foil experiment he discovered the possitive charge at the center of an atom. -
Niels Bohr
Niels Nohr develops an explaination of the atomic structure that became the basis of the periodic table. -
James Chadwick
Chadwick used alpha particles to discover the neutron.