Atomic Theory

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In its most basic form, atomic theory is a theory of the nature of matter that simply states that matter is composed of discrete units called atoms. There have been many theories related to atoms, some dating back to the 6th century B.C. To understand modern atomic theory you have to read up on John Dalton’s theory on the subject.

John Dalton is considered to be the father of modern atomic theory. His efforts took what was an abstract thought to concrete evidence. He began his work as a chemist interested in the behavior and properties of gases. This work helped him make his first break through. He discovered the partial pressure of gases. This led him to to formulate a working theory of the atom. After noticing that certain gases maintained the same ratio in a mixture regardless of the amount of the gas, he began to believe that this ratio stayed constant because the gas was the same down to the atomic level.

As he worked on and developed his theory, Dalton postulated four axioms: elements are made up of atoms, all atoms in an element are identical, atoms of different elements can be identified by their atomic weight and that atoms of different elements can be combined by chemical reaction to form chemical compounds in fixed ratios. He also theorized that atoms could not be destroyed, created, or divided since they are the smallest particles. The last idea has been partially disproved. While atoms can not be destroyed or created in a chemical reaction, they can be by nuclear fission or in a particle collider.

Many physicists have expanded on this basic atomic theory, but no one has completely eliminated its relevance. Niels Bohr developed the Bohr atomic theory that helped science to understand quantum physics better. Others have adapted the theory for other purposes, but they are all just mathematical manipulation of this basic theory to explain phenomena at hand.

Here on Universe Today we have a couple of great articles related to atomic theory: one is about John Dalton’s atomic model and the other is about Mr. Dalton himself. Astronomy Cast offers a good episode that takes us deep inside the atom.

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