For pt. III see abstr. A14127 of 1970. Multiconfiguration Hartree-Fock calculations are given to study term-splittings, electron-affinities and ionization energies for the 2p3 isoelectronic series (Z=6.0 to 30.0) and 2p4 series (Z=7.0 to 30.0). The contribution to the correlation energy of the configurations used has also been analysed. The predicted multiconfiguration Hartree-Fock term splitting ratios for the 2p3 configuration are in good agreement with experiment and in much better agreement than the Hartree-Fock values. This is also true for the individual 4S-2D and 4S-2P transition energies. For the 2p4 series, the predicted term splittings are not as good as for the 2p3 series. Ionization potentials for the 2p3 and 2p4 series, are given up to Z=30. The computed ionization potentials and the electron affinities of C and N are compared with experiment. The Z dependence of the computed ionization potentials is discussed. The results are not in as good agreement, relatively, for the electron affinities of C and N as for the ionization potentials but the absolute errors are roughly the same.