We formulate the probability distribution of orientations and conformations of flexible chains by explicitly taking into account short range repulsions and el ectrostatic interactions with the solvent molecules. The theory is used calculate the segmental order parameters associated with proton NMR measurements on n-alkanes and to study the apparent shift of the gauche-trans energy in the nematic phase. The foundation of the modular description of chain ordering is investigated in the light of the above developments. Excluded volume and electrostatic effects on the conformation energy of dimethoxyethane are evaluated.