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101
Thales of Miletus - 620 BC
First person to wonder what made up the world around us -
102
Democritus - 440 BC
First person to think of an atom (first atomic theory and came up with the word "atom") -
103
Aristotle - 340 BC
First person to believe that all substances are made up of fire, water, air, or earth, and he did not believe in the atomic theory -
104
Sir Isaac Newton - 1704
Believed in the atomic theory and agreed with Democritus; Said that matter is formed by solid massy particles (atoms) and he contributed to the idea that atomos are held together by forces -
105
John Dalton - 1803
Dalton's Atomic Theory
1. All matter is made up of tiny particles called atoms.
2. All atoms of a given element are alike, but different from the atoms of any other element.
3. Compounds are formed when atoms of different elements combine in fixed proportions.
4. A chemical reaction involves a rearrangement of atoms, not a change in the atoms themselves.
* first person to have proof that there is such thing as an atom by performing Atomic Theory Experiment -
106
Henri Becquerel - 1896
First person to discover that an element could be radioactive (didn't know why) based off the results of his Uranium Experiment -
107
J.J. Thompson - 1897
First person to discover the electron and develop the Plum Pudding Model based off the results of the Cathode Ray Tube experiment -
110
Niels Bohr - 1913
Thought that electrons traveled in orbits -
111
Francis Aston - 1919
Invented the mass spectograph and discovered that there were isotopes -
112
Erwin Schrödinger - 1926
Used math equations to find the probablility an electron would be in a certain position and created the Quantum Mechanical Model of the Atom -
113
James Chadwick - 1932
First person to discover the neutron and created the Atom Planetary Model -
Robert Millaken - 1908
First person to discover the charge of individual electrons using the Oil Drip Experiment -
Ernest Rutherford - 1910
First person to discover the nucleus using his Gold Foil Experiment and is credited with the discovery of the proton
