Chapter 12, Problem 121E

Interpretation Introduction

Interpretation: Whether general trends in atomic radius and ionization energy confirm with indicated data should be found and explained.

  $\begin{array}{ccc}\text{Element}& \begin{array}{l}\text{Ionization}\\ \text{Energy}\left(\text{kJ/mol}\right)\end{array}& \begin{array}{l}\text{Atomic}\\ \text{radius}\left(\text{pm}\right)\end{array}\\ \text{Li}& 520& 152\\ \text{Na}& 495& 186\\ \text{K}& 419& 227\\ \text{Rb}& 409& 247\\ \text{Cs}& 382& 265\end{array}$

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 contains one or two electrons, the minimum ionization energy is required to remove the electron because noble gas configuration can be attained upon loss of those electrons.