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492 BCE
Democritus
He believed an atam was the smallest particle of matter. His atomic structure was just a sphere with no electrons, protons, or neutrons -
Antoine Lavoisier
Lavoisier discovered that matter is conserved in a chemical reaction. -
John Dalton
He proposed that that all atoms of an element are identical and all the atoms that make up and element have the same mass. -
Dmitri Mendeleev
Created the first periodic table with the few elements there were -
Eugen Goldstein
Discovered canal rays which were positively charged ions that went through the cathode. -
Robert Millikan
Millikan discovered the charge of electrons with the oil drop apparatus. The charge of an electron is 1.602×10-19 coulomb. -
Ernest Rutherford
Created the atomic model in 1911, believed that electrons orbited around the nucleus like planets around the sun. -
Henry Moseley
Created the atomic battery by pulling electrons back into nuclear form with high voltage -
Niels Bohr
Bohr was Nobel prize winner and contributed to studies on the quantum theory. His atomic model shows the atom as small, positively charged nucleus surrounded by orbiting electrons. -
Max Planck
Created the quantum theory by discovering that a photon of light was carried by a quantum of energy -
Werner Heisenberg
Discovered a way to formulate the quantum theory -
Erwin Schrodinger
Took Bohr’s atomic model further, instead created the quantum mechanical theory -
James Chadwick
Chadwick discovered the neutron. Which he announced as an uncharged particle inside the nucleus. -
JJ thomson
Thomason's model was known as the plum pudding model. His model shows the atom as positively charged, with negatively charged particles within it.
