-
450 BCE
Thought matter was indivisible “atomos”
Democritus -
Proposed the Law of Conservation of mass
Antoine Lavoisier -
roposed the Law of Definite Proportions
Joseph Proust -
Proposed the first Atomic Theory
John Dalton -
Discovered Cathode Rays and the Cathode Ray tube
William Crookes -
Published the FIRST periodic table
Dmitri Mendeleev -
Organized the periodic table by atomic number
Henry Moseley -
Discovered the phenomenon of natural radioactivity
Henri Becquerel -
Performed the Cathode Ray Tube Experiment
J.J. Thomson -
Discovered electrons’ mass & charge
J.J Thompson -
Discovered the electron
J.J Thompson -
Proposed the Plum pudding model of the atom
J.J Thompson -
Discovered two elements, Po and Ra
Marie Curie -
Performed the Gold foil Experiment
Ernest Rutherford -
Performed the Oil Drop Experiment
Robert Millikan -
Discovered the nucleus
Ernest Rutherford -
Proposed the planetary or solar system model of the atom
Niels Bohr -
Proposed the electron cloud model of the atom
Werner Heisenburg -
Discovered the neutron
James Chadwick
