The Chemistry Timeline

• 600 B.C. Thales Idea that water is the main form of matter.
• 546 B.C Anaximenes Idea that air is the main form of matter.
• 450 B.C. Empedocles Idea that the four elements - earth, air, fire and water combine in different proportions.
• 420 B.C. Leucippus and Democritus Idea of the atom or the Age of Atomism.
• 1661 Robert Boyle The Sceptical Chymist.
• 1766 H. Cavendish Discovery of hydrogen.
• 1775 A. Lavoisier Discovery of the composition of air.
• 1800 John Dalton Proposed the Atomic Theory.
• 1820 John Jacob Berzelius devised the modern symbols of elements.
• 1869 Dmitri Mendeleev Periodic Law and designed the Modern Periodic Table of Elements.
• 1886 Eugene Goldstein naming of cathode rays and discovery of proton.
• 1897 J.J. Thomson proposed the structure of the atom - discovery of electron.
• 1911 E. Rutherford proposed the nuclear atom - discovery of a nucleus.
• 1913 Niels Bohr proposed the energy levels in atoms.