A molecule is the smallest unit of a substance that retains the properties of that substance.

Neutrons are particles with no charge. Protons are particles with a postive charge, and electrons are particles with a negative charge.

Catalysts are substances that control the rates of chemical reactions.

"Buckyballs" are microscopic spheres of 60 atoms of pure carbon in a spherelike structure that resembles a geodosic dome. Also called fullerenes or buckminsterfullerenes, they were named after R. Buckminster Fuller who invented the geodosic dome. Buckyballs are of great interest to scientists because they contain a cavity large enough to hold other elements, even whole molecules. Once an element has been deposited into the cavity, it cannot emerge without being heated to high temperatures. This technology may someday be used to deliver medication to specific locations within the body.

A battery is an electrochemical cell in which terminals are connected to electrodes immersed in a solution of electrolytes.

Hess's Law states that the amount of heat needed to change one substance to another depends on the substances and not on the reactions involved.

English chemist and physicist Henry Cavendish not only discovered hydrogen, but also determined the mass of the Earth.

Inert matter does not enter chemical reactions.

Liquids have a definite volume but no definite shape. Because the intermolecular forces are weak in a liquid, it is able to change its shape to conform to its container.

The temperature at which a gas becomes a liquid is its condensation point.