-
330
Four Element Theory
Aristotle proposes the four element theory: earth, air, fire & water -
440
Idea of the Atom
Democritas and Leucippus proposed the idea of an atom -
The Sceptical Chymist
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 -
Dalton;s Law
John Dalton proposed "dalton's Law" describing the relationship between the compnents in a mixture of gases. -
Table of Atomic Weights
Jakob Berzelius developed a table of atomic weights & introduced letters to symbolize elements -
Mendeleev's Periodic Table
First Organized Periodic Table -
Noble Gases Discovered
William Ramsay discovered the Noble Gases. -
Discovery of the Electron
J.J. Thomson discovered that the atom had Electrons -
Source Of Radiation Discovered
Ernest Rutherford discovered the source of radioactivity as decaying atoms -
Planetary View
It was thought that Electrons orbited the Nucleus like planets orbited the sun. -
Discovery of the Proton
Rutherford discovered that an atom contained a proton -
Discovery of the Neutron
James Chadwick discovered that an atom has Neutrons
