This is the first in a series of three recorded lectures about valence and atomic structure given by Linus Pauling when he was a professor of chemistry at the California Institute of Technology. In this lecture, Pauling explains the basics of atomic structure and the correlation between the structure of an atom and the properties that element will manifest (like hardness or pliability). He also covers some scientific history, explaining the ways chemists have discovered the connections between structure and elemental properties, like the discovery of different kinds of valence bonds, Niels Bohr's discoveries of the structure of an atom, and the movements of electrons. Pauling demonstrates all of this with drawings, large molecular models, and samples of minerals, including diamond and asbestos.