John Dalton is often known as “the weather pioneer who advocated atomic theory”. Dalton was very interested in meteorology from a very young age. He kept records of local weather conditions—temperature, wind, humidity, atmospheric pressure—using instruments that he made himself. His meteorological studies assisted him in developing the theory about water vapour and mixed gases in 1801. This theory came to be known as the theory of partial pressures, which says that each component puts forth the same pressure as it would if it made up the whole volume of the mixture alone. At this point, Dalton concluded that all matter consists of small particles.

In 1800, he studied the cooling and heating  of gases which occurred from compression and expansion. The law of thermal expansion of gases was created by him in 1801. In 1804, he studied the effect of temperature on the pressure of a vapour. He wanted to explain why elements of a gaseous mixture remained mixed homogeneously rather than forming layers according to their density.

Dalton’s greatest achievement as the development of the atomic theory. Dalton basically wanted to explain that elements differ because of the way their particles differ.

Dalton’s Model of Atoms

His atomic theory stated that:

1) All matter is made of atoms, which are indestructible and invisible.

2) All atoms of a given element are identical in mass and properties

3) A combination of two or more different kinds of atoms forms a compound.

4) A rearrangement of atoms is known as a chemical reaction.

The modern atomic theory is slightly more involved than Dalton’s but his did help create a basis for current science.

His main contribution was to consider the relative characters and sizes of atoms and they fit together. For example, he knew that hydrogen was the lightest element so he gave it an atomic weight of one. He also believed that water consisted of seven parts of oxygen to one of hydrogen; he thus gave oxygen an atomic weight of seven.

He was not always accurate, but he did form the basis for all modern science.