Dirac-Fock and Hartree-Fock calculations have been performed for the ground state of the HO, HS, HSe, HTe, and HPo molecules. Equilibrium geometries, atomization energies, and ionization potentials, with both methods, are evaluated, compared, and discussed. Calculations on the molecules H(2)M (M=O, S, Se, Te, and Po) have been already published [L. Pisani and E. Clementi, J. Chem. Phys. 101, 3079 (1994)], therefore, the results of the two series of molecules are compared. The effects of electronic correlation have been estimated by using the k-functional technique [L. Pisani, L. De Windt, and E. Clementi, Int. J. Quantum Chem. (in press)]. The agreement with the experimental data, available for low Z, is satisfactory.