Explosives

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 gasses 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. This split-second chemical reaction results in a small amount 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 of particular heavy atoms are split apart, or when the nuclei of certain light elements are forced together. These nuclear processes, called fission and fusion, release thousands or even millions of times more energy than chemical explosions. A single nuclear explosive can destroy an entire city and rapidly kill thousands of its inhabitants with lethal radiation, intense heat and blast effects.

Chemical explosives are used in peacetime and in wartime. In peacetime they are used to blast rock and stone for mining and quarrying, project rockets into space, and fireworks into the sky. In wartime, they project missiles carrying warheads toward enemy targets, propel bullets from guns, artillery shells from cannon, and provide the destructive force in warheads, mines, artillery shells, torpedoes, bombs, and hand grenades. So far, nuclear explosives have been used only in war.