The American Heritage Science Dictionary defines a chemical as "a substance having a specific molecular composition, obtained by or used in a chemical process." As such, a chemical can be an element, in that it has a specific molecular composition and may be produced by a natural chemical process. A chemical compound will have more than one element.

An element is a chemical substance made of specific kinds of atoms that cannot be broken down any further. In short, they are the purest forms of chemicals known to man. Chemical compounds exist to combine different elements, which produce different reactions.

The study of chemical substances is called chemistry. Often, the most basic forms of chemistry classes begin in high school and then continue on throughout higher learning institutions. Those who need a background in chemistry include doctors, pharmaceutical researchers, and even food and synthetic food developers.

In order to produce chemical compounds, it is first necessary to come up with a chemical formula. This formula is merely a listing of atoms, the types of atoms, and the number of those specific atoms needed to form a molecule of the substance in question. Usually, this is accomplished by listing the type of atom first, followed by the number of atoms needed for that particular chemical compound.

For example, consider one of the most common chemical formulas known to the world H₂O. This is two atoms of hydrogen combined with an atom of oxygen. It also gives one of the most basic, life-sustaining chemicals known to mankind -- water.

The order of elements in a chemical formula is usually determined by the Hill system, which states that all carbon atoms will be listed first, hydrogen atoms second, then all other remaining atoms alphabetically. The exception to this is ionic compounds, which will always list the positively charged ion first. This is the case for NaCl, the formula for salt.

Chemicals are used as a basic function of everyday life. From the water one drinks to the gasoline that provides an automobile its energy, they play an integral part in our lives. While common chemicals will continue to play a large role in our lives, more chemicals are coming into existence every day.

Today, many of the chemicals we take for granted and are used did not exist even 100 years ago in a known form. These include everything from medicines to cleaning supplies. The use of chemicals to promote and enhance a greater quality of life for not only the human race, but countless other species, is perhaps man's greatest contribution to the world.

However, while a chemical can be a good thing, certain kinds of chemicals can also have negative effects both on people and the environment. Chemists, or those who work with chemicals, are charged with understanding how different chemicals will react with each other. Without this knowledge, it is very possible experimenting with certain chemicals can lead to catastrophic results.