When he graduated as a chemical engineer, Linus' mother wanted him to come home and make money, perhaps as a secondary school teacher. But, from reading some of the textbooks in college, Linus realized that he wanted to do research. His abilities and test scores were good enough to get him admitted to a PhD program at Caltech (California Institute of Technology). He obtained his PhD at age 24. 

One reason he chose Cal Tech was because they had a professor, Alfred Noyes, who specialized in the study of atom bonding.  After graduation, Linus went to Europe for three years to conduct research in laboratories that were at the cutting edge of research on atomic structure. He then went back to Cal Tech as a faculty member and rose to the rank of full professor in only three years.

In the same year in which he was promoted to professor, Pauling published the paper that made him famous: "The Nature of the Chemical Bond." At age 32, Linus was inducted into the National Academy of Science, becoming the youngest person to ever be admitted. In his research, Pauling used the latest ideas about atoms to explain how atoms share electrons and how this sharing formed a bond to make a molecule. This is common knowledge today, but we forget that we owe these ideas largely to Linus. This work was the basis for Linus receiving the Nobel Prize in chemistry in 1954.

Linus showed scientists how to study molecules and how to measure the angles, bond energies, and distances between the atoms in a molecule. One of his key ideas was to make a "footprint" of the structure of molecules from the   pattern formed by a stream of x-rays as it passes between atoms in the molecules of a sample. The technique is called x-ray diffraction. Atoms in a molecule affect the path of the x-rays in such a way that the pattern reveals the inner structure of the molecule. Before he was 40 years old, Linus had made many major discoveries in chemistry. He showed how molecules participate in chemical reactions, how magnetic fields affect molecules, how atoms attract extra electrons, and how atoms become polarized with negative and positive regions.