Chapter 4, Problem 4.1P

Interpretation Introduction

Interpretation:

In the order of increasing first ionization energy, the given species below has to be arranged.

    $\text{He}\text{Be}\text{Kr}\text{Ne}$

Concept Introduction:

Ionization energy is the minimum amount of energy that is required to remove a valence electron from a neutral atom in gaseous atom or ion.  In the periodic table a trend is present for the ionization energy across the period and down the group.  Ionization energy increases across the period as electrons are added to the same orbital and there is an increase in effective nuclear charge.  Ionization energy decreases down the Group as electrons are added to next orbital.

Explanation of Solution

Given species are shown below.

    $\text{He}\text{Be}\text{Kr}\text{Ne}$

Among the given species, beryllium $\text{(Be)}$ belongs to Group 2 in periodic table.  Helium $\text{(He)}$, krypton $\text{(Kr)}$, and neon $\text{(Ne)}$ belongs to Group 18 (noble gas) in periodic table.  Moving from left to right across the period, ionization energy increases.  Therefore, beryllium is the species that has least ionization energy.  Helium, krypton, and neon are present in the same group.  As moving down the Group, ionization energy decreases.  Therefore, helium has more ionization energy followed by neon and then by krypton.  The increasing order of ionization energy for the given species can be depicted as shown below.