-
300
Aristotle
300 BC Rejected Democritus' idea of atoms ad said that all things were made of proportions of water, earth, fire, and air. -
400
Democritus
400 BC
Came up with the first theory that everything is made up entirely of indivisible elements called atoms -
Isaac Newton
Early 1700's AC Said that the the universe is mechanical and is composed of small moving masses -
Antione Lavoisier
Late 1700's Clarified the concept of elements being simple substances tat cannot be broken down -
Joseph Proust
Early 1800's
Said that the composition of a substance was always the same [constant composition] -
John Dalton
Early 1800's Proposed theory of multiple proportions
it said that all matter is made of atoms, that atoms are indivisible and indestructible ,that all atoms of a given element are identical in mass and properties ,that compounds are formed by a combination of two or more different kinds of atoms, and that a chemical reaction is a rearrangement of atoms. -
JJ Thomson
Around 1890
Discovered the electron and created the plum pudding model -
Max Planck
Invented quantum theory -
Ernest Rutherford
Discovered the orbital theory of the atom -
Albert Einstein
Created the theory of relativity -
Niels Bohr
Quantum Theory of Matter -
James Chadwick
Discovered the Neutron
