Matter & Energy

Matter is composed of atoms or groups of atoms called molecules. The arrangement of particles in a material depends on the physical state of the substance. In a solid, particles form a compact structure that resists flow. Particles in a liquid have more energy than those in a solid. They can flow past one another, but they remain close. Particles in a gas have the most energy. They move rapidly and are separated from one another by relatively large distances.


Gunpowder, explosive powder used in ballistics, specifically, black powder, an explosive mixture of about 75 percent potassium nitrate, 15 percent charcoal, and 10 percent sulfur. Gunpowder was the first explosive known. The formula for gunpowder appears in the writings of the 13th-century English monk Roger Bacon, but it seems to have been discovered by the Chinese, who had used it in firecrackers several hundred years before his time. Gunpowder was probably introduced into Europe from the Middle East. Berthold Schwarz, a German monk of the early 14th century, may have been the first person to employ gunpowder for propelling a projectile. Whatever the precise dates and identities of its first discoverers and users, it is certain that gunpowder was manufactured in England in 1334 and that powder-manufacturing plants existed in Germany in 1340. In the time of Elizabeth I, queen of England, the manufacture of gunpowder was conducted as a monopoly of the crown. Regulations relating to gunpowder in England date from about 1623. It was the only explosive known until the discovery of fulminating gold, a powerful explosive first used in 1628 in European wars. See also Explosives.