-
330
Aristole 330 B.C.
Introduced the four elements theory:
Earth, Air, Fire, Water -
440
Democritus 440 B.C.
He introduced the idea of an atom -
Sir Francis Bacon 1605
He introduced The Proficience and Advancement of Learning which contained a description of what would later be known as the scientific method -
Robert Boyle 1661
Published the Skeptical Chemist
also had some of the earliest thouhts about atoms -
Henry Cavednish 1766
Discovered Hydrogen as a colorless odourless gas that burns and can form an explosive mixture with air -
Antoine Lavoisier 1778
wrote the first extensive list of elements containing 33 elements & distinguished between metals and non-metals -
Jacob Berzelius 1828
developed a table of atomic weights & introduced letters to symbolize elements -
John Newland Lother Meyer Dimitri Mendeleev 1864
arranged the known elements in order of atomic weights & observed similarities between some elements
Lothar Meyer develops an early version of the periodic table, with 28 elements organized by valence
Dmitri Mendeleev produced a table based on atomic weights but arranged 'periodically' with elements with similar properties under each othe -
William Ramsay 1894
discovered the Noble Gases -
Marie Curie 1898
isolated radium and polonium from pitchblende -
Ernest Rutherford 1900
discovered the source of radioactivity as decaying atoms -
Henry Mosely 1913
determined the atomic number of each of the elements and modified the 'Periodic Law