Completely updated and revised, the fourth edition of "The Facts On File Dictionary of Chemistry examines this popular science subject in clear, easy-to-follow prose. Approximately 280 new entries have been added to reflect new information and current entries and back matter have been revised as needed. Pronunciation symbols are now included and many photographs have been replaced. Ideal for high school and college courses, this dictionary is an invaluable reference source for anyone with an interest in chemistry.