Abstract: The 20th century chemistry has accomplished two cross-disciplin ary synthesis in despite of its unprecedentedly fast ramification and specialization. In the first half of the century, Chemistry absorbed the achievement of the revolution of physics. New-born quantum chemistry and modern structural chemistry addressed the questions as to the exact way of combination among elemental matters at the level of electrons. In the second half of the century, chemistry was applied to biology and molecular biology has developed. The phenomena of life can therefore be explained in terms of the delicate structures of molecules. Linus Pauling(1901-1994), the presumably most eminent chemist of the twentieth century, took active part in and essential lead on both of the theoretical upheavals. This study explores Pauling’s work on chemical bonds, early molecular biology and molecular medicine. By doing this, it examines some fundamental conceptual transformation and methodological feature of the two cross-disciplinary synthesis. 

Key Words: Synthesis of disciplines; Chemical bonds; Molecular biology; History of chemistry; 20th century