jan 1, 1803 - John Daulton's Atomic Theory
Daulton's atomic theory was discovered in 1803. Through experiments, he concluded that all matter was composed of tiny particles called atoms and that these particles are indivisible and indestructible. Also included in the theory was that atoms of the same element are identical, and ones that aren't are all different. The picture below shows that everything, even pencils are composed of atoms.
Added to timeline:
Atomic Theory Timeline - Adrianne Moran 4th Period Chemistry