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.


Toluene, colorless hydrocarbon, occurring in coal tar, specific gravity 0.86, boiling point 110.6° C (231.1° F). Toluene is sometimes called toluol or methylbenzene. The name toluene reflects the way in which it was once prepared, through destructive distillation of balsam of tolu. A great deal of industrial toluene is prepared in oil refineries by the alkylation of benzene. It is used as a solvent and as a source of synthetic compounds, for example, in the production of trinitrotoluene. Prolonged breathing of toluene vapor is harmful and should be avoided.