Encyclopedia of Science | Atom

• History
• Modern models of the atom
• Physical dimensions

An atom is the smallest particle of a element that has all the properties of that element. Imagine that you decide to cut a chunk of aluminum metal into half, over and over again. At some point, you would need very small tools to do the cutting, tools smaller than anything that really exists. However, you would eventually get to the very smallest piece of aluminum that still has all the properties of the original chunk. That smallest piece is an atom of aluminum.

History

One of the questions that ancient Greeks thinkers debated was the structure of matter. Is matter, they asked, continuous or discontinuous? That is, in the aluminum example mentioned above, can a person continue to cut a chunk of aluminum into smaller pieces...