Chapter 7, Problem 84A

Interpretation Introduction

Interpretation : The octet rule explains the large increase in energy between the first and second ionization energies of Group 1A metals is to be related.

Concept Introduction : The minimal amount of energy an electron in a gaseous atom or ion must absorb to escape the influence of the nucleus is known as the ionization energy. Atoms frequently acquire the noble gas's electron configuration according to the octet rule. Eight sets are called an octet.

Answer to Problem 84A

The Group 1A elements have only one valence electron so the first ionization energy is low and it is difficult to remove an electron from the octet configuration, so there is a large increase in the second ionization energy.

Explanation of Solution

The elements such as lithium, sodium, potassium, rubidium, caesium, and francium belong to Group 1A elements. All these elements have one valence electron in the valence shell. According to the octet rule, the valence electrons lose to attain the noble gas configuration.

Since there is only one valence electron, it is easy to remove that electron and so the first ionization energies are of lower energy.

After the first ionization energy, all the elements have achieved the noble gas configuration.

For the second ionization energy to take place, there should be the removal of one more electron from the valence shell that is completely filled.

There is a need for high energy in order to remove an electron from the fully filled shell, so there is a large increase in energy between the first and second ionization energies.