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300
Democritus suspects atoms
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300
Aristotle Says different
Aristotle says his theory of the atom to change everything. -
Dalton's 5 Postulates
1)All Atoms of any one element are exactly alike in all aspects; in particular, same weight.
2)Atoms of different elements have different properties; in particular, different weight.
3)A compound, as distinguished from an element is composed of a certain definite integral number of atoms of each of the elements present.
4)In the chemical reactions that may occur, none of the atoms are destroyed and no new ones are created.
5)When elements react, their atoms sometimes combine in more than one -
John Newlands
John Newlands publishes his incorrect periodic table -
Crooke's Tubes
Used cathode rays tubes and discovered cathode rays which indicated that different atoms were of the same material. -
JJ Thomson electron
Discovered the electron using Crooke's tubes. -
Mendeleev table
Mendeleev creates the first correct periodic table -
Rutherford nucleus
Rutherford discovers the nucleus during an experiment. -
Bohr
Bohr discovers the proton.
