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.


Ketones, class of organic compounds of the general structure R—CO—R’, in which R and R’ represent organic radicals. The simplest ketone, acetone (CH3—CO—CH3), corresponds to the general ketone formula, with three hydrogen atoms attached to each of the end carbon atoms. Acetone is a product of the metabolism of fats, but under ordinary conditions it oxidizes quickly to water and carbon dioxide. In diabetes mellitus, however, acetone accumulates in the body and may be detected in the urine. Other ketones are camphor, many steroids, some fragrances, and some sugars. Ketones are relatively reactive organic compounds and thus are invaluable in synthesizing other compounds; they are also important intermediates in cell metabolism.