The general public often construes the word "chemical" to mean a harmful synthetic substance. In fact, however, the term applies to any element or compound, either natural or synthetic. The thousands of compounds that make up the human body are all chemicals, as are the products of scientific research. A more accurate description, however, can be found in the dictionary. Thus, aspirin is a chemical by this definition, since it is the product of a series of chemical reactions.

The story of chemicals began with the rise of human society. Indeed, early stages of human history, such as the Iron, Copper, and Bronze Ages reflect humans' ability to produce important new materials. In the first two eras, people learned how to purify and use pure metals. In the third case, they discovered how to combine two to make an alloy with distinctive properties.

The history of ancient civilizations...