Narrator: X-ray diffraction with crystals was a new technique when Pauling first put it to use in 1922 at Caltech. A beam of x-rays
is passed through a crystal. The atoms in the crystal deflect the x-rays onto a photographic plate. From the pattern on the
photograph, it is possible to work out the molecular structure of the crystals. Such as the glycine molecule. That is, the
distance between the atoms, and the angles between the bonds holding the atoms together. Pauling added another dimension to
his work: the mathematically difficult area of quantum mechanics, then a new branch of physics. Combining quantum mechanics
with x-ray diffraction led him to a powerful new theory on the nature of the chemical bond.
Linus Pauling: Finally, in December 1930, one day, I thought of a way to get around the mathematical difficulties – a simplification which
made it very easy to get results. And I was so excited and happy I think I stayed up all night making, writing out, solving
the equations which were so simple that I could solve them in a few minutes. Solve one equation, and get the answer and solve
another equation about the structure of octahedral complexes such as the ferrocyanide ion in potassium ferrocyanide, or square
planar complexes such as in a tetracholoroplatinate ion and various other problems. I just kept getting more and more euphorious
as time went by and it didn’t take me long to write a long paper about the nature of the chemical bond, and that was a great
Narrator: That experience helped revolutionize chemistry. It led science to a new understanding of both the structure and behavior
of all matter.