Relationships between the Properties of Families of Materials

A general and useful regularity exists between the properties of families of chemical species: the properties of the members of one family are shown to be simply, and approximately linearly, related to the properties of analogous materials in similar families. As examples, the phenomenon is shown to enable accurate predictive correlations from small amounts of data for the liquid/vapor critical temperatures of several families of organic molecules and for the normal boiling temperatures of SF 5 - and CF 3 -containing compounds.