Chapter 12, Problem 107E

Interpretation Introduction

Interpretation: Values of first ionization energies for arsenic and selenium as $0.947\text{ MJ/mol}$ and $0.941\text{ MJ/mol}$ should be rationalized in terms of electron configuration.

Concept introduction: In order to remove the electron situated in outermost shell certain minimum energy must be imparted to convert an atom to gaseous species. The energy thus imparted represents ionization energy.

The magnitude of ionization energy is determined by how effectively valence electron is held by the nucleus. If the outermost shell has, for instance, one or two electrons that require very minimum ionization energy as they can attain the noble gas configuration upon loss of those electrons.