Democritus theorizes an indivisible particle which he names the atomos.
Expanded on Democritus's theory.
Dobereiner creates law of triads.
Newlands creates law of octaves.
Mendeleev organises elements by atomic mass and properties, creating the framework for the periodic table we see today.
Meyer had ideas similar to Mendeleev, but was afraid to publish them. He made a graph that listed the relations between atomic mass and number.
DIscovered the noble gas argon with Ramsey.
Discovered argon with Rayleigh and went on to discover other noble gases.
Created plum pudding model.
Created the Rutherford model where electrons rotated around a positive nucleus.
Discovered that amount of protons equals atomic number.
Created planetary model.
Discovered trans-uranium elements and discovered isotopes.