Dielectric. Molecular graphic of a type of dielectric called fluorine-doped glass. The molecular structure of this material is similar to glass, but fluorine atoms (purple) are substituted for some of the oxygen atoms (red). Silicon atoms are shown in yellow. The blue lines show the complex build up of charge around the fluorine layer. Dielectrics are substances that conduct electricity more weakly than metals. This dielectric has important applications in the semiconductor industry.