4.1  Studying Atoms (continued)

Ancient Greek Models of Atoms

If you cut a piece of aluminum foil in half, you have two smaller pieces of the same shiny, flexible substance. You could cut the pieces again and again. Can you keep dividing the aluminum into smaller pieces? Greek philosophers debated a similar question about 2500 years ago.

The philosopher Democritus believed that all matter consisted of extremely small particles that could not be divided. He called these particles atoms from the Greek word atomos, which means “uncut” or “indivisible.” He thought there were different types of atoms with specific sets of properties. The atoms in liquids, for example, were round and smooth, but the atoms in solids were rough and prickly.

Aristotle did not think there was a limit to the number of times matter could be divided. Figure 1 shows the model Aristotle used to describe matter. For many centuries, most people accepted Aristotle's views on the structure of matter. But by the 1800s, scientists had enough data from experiments to support an atomic model of matter.

Figure 1  Aristotle thought that all substances were built up from only four elements—earth, air, fire, and water. These elements were a combination of four qualities—hot, cold, dry, and wet. Fire was a combination of hot and dry. Water was a combination of cold and wet.