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100
Democritus
He created the first atomic model, he relied only on human sences to study it. -
101
Aristotle
He developed a theory that was based around the four elements; fire, water, earth & air. He also beleived that these elements had four qualities; dryness, moistness, hotness and coldness -
John Dalton
He proposed his theory on the atom:
1) Matter is made up of of invisible, ins destructible particles.
2) All atoms of an element are identical.
3) Atoms of different elements have different chemical properties.
4) Atoms of different elements combine in simple whole numbers to form compounds.
5) Atoms cannot be created nor destroyed. -
J.J Thomson
Descovered the plum pudding model; that an atom is made up of negatively charged electrons, surrounded by an area of positive charges to balance out the electrons. -
Ernest Rutherford
Discovered that all atoms have a nucleus. He later discovered that this nucleus is full of sub-atomic particles called protons. He did this using the gold-foil experiment or the Rutherford experiment. -
Niels Bohr
Drew a picture of the atomic structure using Rutherfords amazing new discovery -
James Chadwick
He proved the existence of neutrons. He used radioactive elements to do this.