Chapter 9, Problem 132A

Interpretation Introduction

Interpretation:

The formation of positive and negative ions needs to be explained.

Concept introduction:

Formation of ions takes place when atom gain or loss electrons to attain stable octet electronic configuration. The ions formed can be positively or negatively charged.

Answer to Problem 132A

Cation is formed when an atom loses one or more valence electrons in order to obtain stable octet. An anion is formed by gaining one or more valence electrons.

Explanation of Solution

Let the example of sodium to see the formation of positive ion. Electron configuration of Na is given below.

${\text{Na=1s}}^{\text{2}}{\text{2s}}^{\text{2}}{\text{2p}}^{\text{6}}{\text{3s}}^{\text{1}}$

Na contain one valence electrons in its 3s shell. It loses it and acquire ${\text{Na}}^{+}$ ion.

Non-metals easily gain electrons to achieve a stable outer electron configuration. Let the example of Cl to see the negative ion formation. Electron configuration of Cl is as follows:

${\text{Cl=1s}}^{\text{2}}{\text{2s}}^{\text{2}}{\text{2p}}^{\text{6}}{\text{3s}}^{2}3{\text{d}}^{\text{5}}$

Total number of valence electrons in Cl is 7. So, it needs one electron to achieve stable electron configuration and formed ${\text{Cl}}^{-}$ ion.

Conclusion

Positively charged ions are known as cation and negatively charged ions are known as anion.