KEY. Development of the ATOMIC THEORY TIMELINE ..., Slides of Chemistry

Download KEY. Development of the ATOMIC THEORY TIMELINE ... and more Slides Chemistry in PDF only on Docsity! What the scientists did in chronological order - KEY. Development of the ATOMIC THEORY TIMELINE Democritus 465 BC  Greek philosopher  Hypothesized that atoms cannot be destroyed, are always moving, and are invisible John Dalton 1803  Created the first real atomic theory  Hypothesized that the atom was a tiny hard sphere  Believed that atoms of a given element are identical Dmitri Mendeleev 1869  Suggested future elements would be discovered and fitted into the periodic table  Proposed the basis of our modern periodic table JJ Thomson 1897  Discovered the electron  Used the cathode ray tube in his discovery  Created the “plum pudding” model of the atom Ernest Rutherford 1911  Discovered that the atom is mostly empty space  Discovered that the proton had a positive charge  Did the gold foil experiment Niels Bohr 1915  Created a model of the atom with electrons moving around the nucleus in fixed orbits Werner Heisenberg 1925  Uncertainty principle: A particle’s position, energy, and time can never be precisely known  Worked with the Quantum Theory of the Atomic Model James Chadwick 1932  Discovered the neutron  Found the missing mass of the atom’s nucleus