-
340
Aristotle
Describes his ideas of five states of matter -
440
democitus
Democritus asserted that there was an infinite number of atoms and that they were so small that their size could not be diminished. -
Sir Francis Bacon
Published "The Proficience and Advancement of learning" which contained a description of the scientiic method -
Robert Boyle
Published "The Skeptical Chymist" which is a treatise on the distinction between chemistry and alchemy. -
Henry Cavendish
Discovered Hydrogen -
Antoine Lavoisier
Wrote first lit of elements which contained 33 elements and seperated them as metals and nonmetals. -
Jacob Berzelius
Developed a table of atomic weights & introduced letters to symbolize elements -
John Newlands
Arranged the known elemnts in order of atomic weights and observed similarities between some elements -
Lother Meyer
Develops the early version of the periodic table with 28 elements organized by valence -
Dimitri Mendeleev
Produced a table based on atomic weights but arranged 'periodically' with elements with similiar properties under each other. His periodic table included the 66 known elements organized by atomic weights -
William Ramsay
Discovered the noble gases -
Marie Curie
Isolated radium and polonium from pitchblende -
Ernest Rutherford
Discovered the source of radioactivity as decaying atoms -
Henry Moseley
determined the atomic number of each of the elements and modified the "Periodic Law"
