Atomic theory

The atomic theory is a theory of the nature of matter. It states that all matter is composed of atoms.

Importance

The importance of this theory cannot be overstated. It has been said, for instance by Richard Feynman that atomic theory is the single most important theory in the history of science. This is due to the wide ranging implications that it has for both pure and applied science.

The entirety of modern chemistry (and biochemistry) is based upon the theory that all matter is made up of atoms of different elements which cannot be transmuted by chemical means. In turn, chemistry has allowed for the development of the pharmaceutical industry, the petrochemical industry, and many others.

Much of thermodynamics is understandable in terms of kinetic theory, whereby gases are considered to be made up of either atoms or molecules, behaving in accordace with Newton's laws of motion. This was, in turn, a large driving force behind the industrial revolution.

Indeed, many macroscopic properties of matter are best understood in terms of atoms. Other examples include friction, material science and semiconductor theory. The latter is particularly important, as it is the foundation of electronics.

History

The existence of atoms was first proposed by Greek philosophers such as Democritus, Leucippus, and the Epicureans, but without any real way to be sure, the concept disappeared until it was revived by Rudjer Boscovich in the 18th century, and after that applied to chemistry by John Dalton.

Rudjer Boscovich based his theory on Newtonian mechanics and published it in 1758 within his Theoria philosophiae naturalis redacta ad unicam legem virium in natura existentium. According to Boscovich, atoms are stuctureless points, which exhibit repelling and attracting forces on each other, depending on distance. John Dalton used the atomic theory to explain why gases always combine in simple ratios. It was with Amedeo Avogadro's work, in the 19th century, that scientists began to distinguish atoms and molecules. In modern times atoms have been observed experimentally.