Chapter 7, Problem 48A

Interpretation Introduction

Interpretation:

The formation of ions by alkali metals and halogens needs to be explained.

Concept introduction:

Many atoms do not have eight electrons in its outermost shell. There may be less than 8 electrons indicating that there is deficiency of 1 or 2 electrons. If atoms gain electrons it becomes positively charged ions and if it gains electrons, it becomes negatively charged ions. Octet rule is applied to each element to get a stable configuration wherein there needs to be 8 outermost electrons.

Answer to Problem 48A

The alkali metal will lose one electron to form an ion while halogen will gain one electron to form an ion such that it attains octet configuration..

Explanation of Solution

Alkali metals are those elements which belong to group 1. Halogens are those elements which belong to group 17.

The electronic configuration of alkali metals is ${\text{ns}}^{\text{1}}$. It has single valence electron in its outermost shell. This one electron can be easily removed to form a positive ion and attain octet configuration.

The electronic configuration of halogens is ${\text{ns}}^2{\text{np}}^5$. It has 7 valence electrons in its outermost shell indicating that there is a deficiency of 1 electron. Hence, it can gain one electron to form a negative ion and attain octet configuration.

Thus, alkali metal will lose one electron to form an ion while halogen will gain one electron to form an ion.

Conclusion

The alkali metal will lose one electron to form an ion while halogen will gain one electron to form an ion such that it attains octet configuration.