An isoelectronic series is a set of atoms or ions that contain the same total number of electrons. The species N3−, O2−, F−, Ne, Na+, and Mg2+ constitute one such series.
Analyze this series with respect to valence and core electrons.
(a) For any three species of your choice from the series, write their ground-state electron configurations.
(b) For each of the six species, identify (i) the number of valence electrons, (ii) the number of core electrons, and (iii) the principal quantum number associated with the valence shell.
(c) Using the results from part (b), explain why all species in the series have identical numbers of valence electrons yet display different first ionization energies.
(d) Rank the six species in order of increasing first ionization energy, providing a detailed justification that references both nuclear charge and electron shielding.