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200
440 BC-Democritus
He named the atom and said the atom could not be cut forever. -
201
300 BC-Aristotle
He disagreed with Democritus and believed that atoms could be cut. -
Dalton
He said all substances are made of atoms, which are small particles and atoms cannot be divided, created, or destroyed. He said atoms are alike in the same elements and different in different elements. He said atoms can make new substances if they are joined together. -
Thomson
He said there are particles inside of atoms, which could be divided. He named the negative charges, electrons. -
Rutherford
He discovered that atoms are mostly empty space with a small part of highly dense matter. -
Rutherford
He described atoms with a dense positive nucleus in the center of the atom. -
Bohr
He said that electrons move along on energy levels, jumping from one level to another level. -
Schrodinger & Heisenberg
They said that electrons do not travel along on paths, but in electron clouds.