Explosives are substances that produce violent chemical or nuclear reactions. These reactions generate large amounts of heat and gas in a fraction of a second. Shock waves produced by rapidly expanded gases are responsible for much of the destruction seen following an explosion.

The power of most chemical explosives comes from the reaction of oxygen with other atoms such as nitrogen and carbon or in the decomposition of solid or liquid compounds to form gases. This split-second chemical reaction results in a small volume of material being transformed into a large amount heat and rapidly expanding gas. The heat released in an explosion can incinerate nearby objects. The expanding gas can smash large objects like boulders and buildings to pieces. Chemical explosives can be set off, or detonated, by heat, electricity, physical shock, or another explosive.

The power of nuclear explosives comes from energy released when the nuclei...