John Dalton (1803)

In 1803 John Dalton was experimenting on gases when he discovered a monumental step in the discovery of the atom and the atomic theory. John had discovered that oxygen mixed with either one or two volumes of nitric oxide (NO) is closed vessels over water. Meaning he could determine the pressure of the gases via the displacement of the water level. Dalton’s law states that the total pressure of a mixture of gases is equal to the sum of the partial pressures of each of the constituent gases. John Dalton inferred that gases were made up of tiny individual particles, thus pushing future scientists towards the discovery of the atom.  

• John Dalton used all his information and created one of the first models of the atom.

• He simply proposed that atoms were tiny, hard spheres that could no be split up.