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400
Democritus
Democritus believed that there were indivisible particles; all matter was made up of these atoms. He thought each atom had unique properties. -
John Dalton
Dalton believed that the atom is an indestructible sphere that has no concept of internal structure all the way through. -
J.J. Thomson
Thomson came up with the idea that the atom consists of positively charged material filled with tiny negatively charged particles - kind of like plum pudding. -
Ernest Rutherford & Niels Bohr
Rutherford and Bohr believe that in an atom, thh epositively charged material is in a tiny nucleus in the centre and the negatively charged electtrons move around it in indefinite circular orbits and the rest is empty space. -
Erwin Schroedinger
Schroedinger said that since electrons are continuously circling the nucleus in the atoms, they form complex regions that look like "clouds". This led to the electron clooud model. -
Aristotle
Aristotle believed all matter was made up of the four elements – air, water, fire, earth which were made up of particles with specific properties.
