He was following the lead of one of his scientific heroes: the legendary, cigar-chomping
head of chemistry at Berkeley, Gilbert Newton Lewis. In the early 1920s, Lewis published an idea about the bonds between atoms that he
had developed with General Electric researcher Irving Langmuir. They theorized that an element’s valence arose naturally from its atomic structure.
Atoms, it was known, consisted of a positively charged nucleus surrounded by negatively
charged electrons. Lewis and Langmuir hypothesized that atoms were most stable when
the electrons orbited the nucleus in shells containing eight at a time (except for
the atom’s innermost shell, which contained two electrons).
According to the Lewis and Langmuir model, if an atom had seven electrons in an outer
shell, it would tend toward collecting an eighth for maximum stability. One way to
do this was to combine with another atom that had one extra electron in its outer
shell. The two atoms would "share" an electron, creating a more stable product. The
resulting "shared electron bond" tied the atoms together into a molecule.
Pauling was intrigued by the Lewis and Langmuir model, but he knew that it was too
simple to explain a number of laboratory observations about real molecules. In addition,
he learned in Europe that the sort of atomic structure Lewis and Langmuir used in
their model — one in which electrons orbited the nucleus like little planets — was
in the process of being discarded. The new quantum physics was bringing to light an
entirely new, paradoxical and exciting view of the atom. And it was on the foundation
of this new science that Pauling intended to build a new understanding of the chemical