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Jan 1, 1000
Democritus 400 BCE
Democritus said that all things are made up of atoms which are indivisible and indestructible. -
Jan 1, 1000
Aristotle 400 BCE
Aristotle believed everything was made up of four specific elements. Earth, water, fire, and air. -
John Dalton
Dalton's theory was that every element was made up of different atoms, specifically with different masses. -
J.J. Thomson
JJ Thomson conducted an experiment with a cathode ray tube, not uncommon at the time. -
Henri Bacquerel
Bacquerel discovered that the rays from uranium are different from X-Rays. They could not be detected by electric or magnetic fields. -
Pierre and Marie Curie
They won a nobel prize for the discovery of radioactivity with Bacquerel. -
Robert Millikan
Did the "Oil Drop Expirement" -
Ernest Rutherford
Rutherford tested Thomson's plum pudding model. -
Niels Bohr
Bohr applied the quantum theory to Rutherford's atomic structure by assuming that electrons travel in stationary orbits. This led to the calculation of energy levels. -
Quantum Model
The quantum model is a probability area an electron may be located in. -
James Chacdwick
Chadwick discovered the nuetron.
