-
330
Aristotle
Proposes the four element theory: earth, air, fire & water -
440
Democritus
Originally came up with the atomic theory -
Sir Francis Bacon
Published "The Proficience and Advancement of Learning" which contained a description of what would later be known as the scientific method. -
Robert Boyle
Published "The Sceptical Chymist" which was a treatise on the distinction between chemistry and alchemy. It also contained some of the earliest ideas of atoms, molecules, and chemical reaction marking the beginning of the history of modern chemistry -
Henry Cavendish
Discovered hydrogen as a colorless, odourless gas that burns and can form an explosive mixture with air -
Antoine Lavoisier
wWote the first extensive list of elements containing 33 elements & distinguished between metals and non-metals -
Jacob Berzelius
Developed a table of atomic weights & introduced letters to symbolize elements -
John Newlands
Arranged the known elements in order of atomic weights & observed similarities between some elements -
Lother Meyer
Develops an 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 similar 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'