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500 BCE
The Alchemists
Discovered a substance that transformed common metals into silver or gold as well as making a basic version of the periodic table. -
428 BCE
Plato
Came up with the idea of elements. -
400 BCE
Democritus
Proposed the existence of atoms. -
Robert Boyle
Discusses the possibility of atoms existing. -
Atone Lavoisier
Proved the Law of Conservation of Matter. -
John Dalton
Proposed that compounds were multiple atoms combined together. -
Billiard Ball Model
Proposed by John Dalton. Earliest model of an atom and therefore very simple. -
Amedeo Avagadro
Realized that elements could exist as molecules. -
JJ Thompson
Determined the charge to mass ratio for electrons. -
Dmitri Mendeleev
Created the modern periodic table. -
Pierre and Marie Curie
Did lots of research into radioactive elements and substances. -
Plum Pudding Model
Proposed by JJ Thompson. Electrons surrounded by a positive charge. -
Albert Einstein
Stated the equivalence of energy and mass as well as proposing the quantum of light. -
Robert Millikan
Discovered the negative charge of an electron. -
Ernest Rutherford
Concluded the nucleus has a positive charge. -
Solar System Model
Proposed by Ernest Rutherford. An earlier version of the electron cloud model. -
Neils Bohr
Proposed that the outer orbit of an atom could hold more electrons. -
Henry G. J. Mosley
Discovered the number of protons in an element and redefined the atomic number. -
Werner Heisenberg
Stated the Uncertainty Principle, one of the foundations of quantum mechanics. -
Electron Cloud Model
Proposed by Erwin Schrodinger and Werner Heisenberg. A nucleus surrounded by quickly moving electrons. -
James Chadwick
Discovered Neutrons. -
Erwin Schrodinger
Made the Schrodinger's cat thought experiment, forming the basics for quantum mechanics.