Chemistry

INTRODUCTION
Chemistry, study of the composition, structure, properties, and interactions of matter. Chemistry arose from attempts by people to transform metals into gold beginning about AD 100, an effort that became known as alchemy (see Chemistry, History of). Modern chemistry was established in the late 18th century, as scientists began identifying and verifying through scientific experimentation the elemental processes and interactions that create the gases, liquids, and solids that compose our physical world. As the field of chemistry developed in the 19th and 20th centuries, chemists learned how to create new substances that have many important applications in our lives.
Chemists, scientists who study chemistry, are more interested in the materials of which an object is made than in its size, shape, or motion. Chemists ask questions such as what happens when iron rusts, why iron rusts but tin does not, what happens when food is digested, why a solution of salt conducts electricity but a solution of sugar does not, and why some chemical changes proceed rapidly while others are slow. Chemists have learned to duplicate and produce large quantities of many useful substances that occur in nature, and they have created substances whose properties are unique.
Much of chemistry can be described as taking substances apart and putting the parts together again in different ways. Using this approach, the chemical industry produces materials that are vital to the industrialized world. Resources such as coal, petroleum, ores, plants, the sea, and the air yield raw materials that are turned into metal alloys; detergents and dyes; paints, plastics, and polymers; medicines and artificial implants; perfumes and flavors; fertilizers, herbicides, and insecticides. Today, more synthetic detergent is used than soap; cotton and wool have been displaced from many uses by artificial fibers; and wood, metal, and glass are often replaced by plastics.
Chemistry is often called the... [continues]

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