The critical constants of the elements

The critical temperatures available in the literature for seventeen elements constitute the basis of this study for predicting critical temperatures from normal boiling points. When not available, the normal boiling point can be estimated from vapor‐pressure data. The extension of the vapor‐pressure data beyond the normal boiling point establishes the critical pressure from the estimated critical temperature. In accordance with this procedure, critical temperatures and pressures have been predicted for thirty‐six elements included in the periodic table from lithium to uranium. These critical constants consitute the core of this study and have been used to calculate both van der Waals' constants. These constants, when plotted against their atomic numbers, produce correlations that may permit the further prediction of van der Waals' constants for other elements. A simple relationship between the critical volume and the volume van der Waals' constant is found to exist and is presented as a basis for predicting the critical volume of elements.