[Moderator's note:  This topic was originally split off from For Questions That Don't Merit Their Own Thread, since the ensuing discussion turned out to be a lengthy one.] Is it possible to calculate the distance between molecules on a metal compound purely by mathematical calculation as long as we know the ratio of the metals used, density and molar mass of each metal as well as the resulting shape of the crystal matrix of the compound? Assuming that the metal constituent is evenly distrib