This booklet is a student manual in a series of booklets that make up the core of a Physical Science course designed for the freshman year of college and used by teachers in the 27 colleges participating in the Thirteen College Curriculum Program. This program is a curriculum revision project in support of 13 predominantly Negro colleges and reflects educational research in the area of disadvantaged youth. This unit covers the fundamental principles of chemistry, including distinguishing features of four chemical classes of elements and patterns and patterns of chemical combinations of elements. Experiments are provided to illustrate the major concepts of chemical combination. (MLH)