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442
Democritus
Democritus came up with the theory that the univerterse is made up of small particles called atoms that also make up all matter. -
Period: 450 to
atomic theory
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Atonie Lavoisier
He is nicknamed the father of chemistry becasue he was the first to come up with the law of conservation of mass but he also proposed the combustion theory. -
John Dalton
John Dalton stated that all matter is composed of very small particles called atoms. Dalton also said atoms cannot be created or destroyed. -
Law of conservation of mass
the law of consewrvation of mass states that matter can neither be creaated or destroyed.- Hermann von Helmholtz stated the law of conservation of mass. -
Dmitri Mendeleev
Dmitri arranged the first periodic table with only 63 elements on the table. He put them in order form increasing atomic weight -
J.J. Thomson
J.J. discoverd that the mass of a charged particle was less than a hydrogen atom and he also created the pium pudding model -
plum pudding model
the pum pudding model was made to show how random the electrons appeard inside the atom all of the atoms in the world have different places for there electrons. -
Cathode ray tube
sir willam crookes discoverd the cathode ray tube. this discoverie later was used in making tvs -
Robert Millikan
Robert discoverd a way calculate the mass of a proton and electron. -
gold foil experiement
Ernest Ruthorford created an expeirement trying to proove that protons are found inside the nucleus and electron are found outside of the atoms nucleus. -
Ernest Ruthorford
Ernest proposed that protons are found inside the nucleus and electron are found outside the nulcleus of the atom. -
Niels Bohr
Neils proposed that electrons travel in an stationary orbit around the atom -
Henry Moseley
Henry determined a way to measure the positive charges in the nucleus of an atom. this it the second concept for the atomic number. -
James chadwick
James discoverd the neutron witch led to fission and that led to the building of the atomic bomb.
