Study of Matter Compounds  Elmhurst College
Atoms Physical Properties Mixtures  Chemistry Department
Elements Chemical Properties    Virtual ChemBook

 

What is an Atom?

COMPOSITION OF MATTER

MATTER is is anything which has weight and occupies space. Matter is all things that we can see, feel, and smell in our daily living. Chemistry is the study of matter. Matter is the "stuff" all around us.

In order to understand the properties and reactions of matter, it must be divided into simpler, less complex substances. It is easier to work with the definitions if we start with the smallest pieces of matter and gradually work up to more complex matter. The development of the Atomic Theory takes this approach.

 ATOM THEORY OF MATTER - History

The earliest ideas about matter and atoms were developed by Greek philosophers between 450 and 380 B.C. At that time, the question under discussion was whether matter had the property of being continuous or discontinuous. These concepts can be visualized if you took the "lead" or graphite of a broken pencil point and divided it in half, then divided that piece in half and again half of that piece. This process could be continued as long as possible. If matter was continuous, the process could be continued indefinitely without ever "running out" of graphite. If matter was discontinuous, then at some point, the dividing process would end when the last particle which could still be called graphite was all that remained. A further division would result in destroying the matter called graphite.

 ATOMS

Democritus used the word "atomos" meaning "indivisible" or "uncuttable" to describe the ultimate building blocks of matter. ATOMS result from the repeated division of matter to very very tiny, permanent, indivisible, invisible bits of matter with definite size and shape. This Atom Theory was applied in support of the Discontinuous Theory of Matter. Since there was no means to test such a hypothesis, other philosophers such as Plato and Aristotle argued for the Continuous Theory of Matter. The Continuous Theory of Matter received wide spread support until the 1800's when John Dalton revived the atom concept to explain certain aspects of chemical reactions.

The final division of matter such as graphite results in atoms of the element carbon.