A simple method is presented for the prediction of PVT behavior and glass transition temperature of polymers over an extended range of external temperatures and pressures from the knowledge of only the molecular structure of their repeating units. Scaling constants of the Lattice Fluid (LF) equation-of-state model of polymers are extracted using experimental PVT data. First-order and second-order groups specific to polymers are identified in their repeating units. These groups can capture even fine structural differences, thus, enabling more precise predictions. A list of these groups is presented along with their contribution to the above scaling constants and the flex energy of the Gibbs-DiMarzio theory for glass transition. Once these parameters are known, the estimation of density and glass transition temperatures of pure polymers is straightforward using the LF theory. The predicted values are in satisfactory agreement with the available experimental ones.