Chapter 6, Problem 71A

Interpretation Introduction

Interpretation:

Atomic size of atoms when silicon is bonded to oxygen is to be explained.

Concept introduction:

Atomic radii of atoms of elements down the group increase as $Z$ increases because new shells are introduced and therefore the distance between nucleus and valence shell increases. Along a period, size or radii decreases as the electrons are introduced into the same shell and are pulled by higher nuclear charge.

Answer to Problem 71A

When silicon is bonded to oxygen it loses 4 electrons so the nuclear pull increases on the valence shell as it becomes ${\text{Si}}^{4+}$, resulting into decrease in its atomic radius. Whereas oxygen gains 2 electron which leads to more repulsion among electron in the valence shell leading to increase in atomic radius of ${\text{O}}^{2-}$.

Explanation of Solution

Atomic number of oxygen and silicon are 8 and 14 respectively. Table indicating their atomic and ionic radius; atomic electronic configuration and ionic electronic configuration are as follows:

$\begin{array}{ccccc}& \begin{array}{l}\text{ATOMIC}\\ \text{ELECTRONIC}\\ \text{CONFIGURATION}\end{array}& \begin{array}{l}\text{IONIC}\\ \text{ELECTRONIC}\\ \text{CONFIGURATION}\end{array}& \begin{array}{l}\text{ATOMIC}\\ \text{SIZE}\\ \left(\times {10}^{-12}\text{m}\right)\end{array}& \begin{array}{l}\text{IONIC}\\ \text{SIZE}\\ \left(\times {10}^{-12}\text{m}\right)\end{array}\\ \text{OXYGEN}& \left[\text{Ne}\right]{\text{3s}}^{\text{2}}{\text{3p}}^{\text{4}}& \left[\text{Ne}\right]{\text{3s}}^{\text{2}}{\text{3p}}^6& 73& 140\\ \text{SILICON}& \left[\text{Ne}\right]{\text{3s}}^{\text{2}}{\text{3p}}^{\text{2}}& \left[\text{Ne}\right]& 118& 41\end{array}$

When silicon is bonded to oxygen it loses 4 electrons so the nuclear pull increases on the valence shell as it becomes ${\text{Si}}^{4+}$, resulting into decrease in its atomic radius. Whereas oxygen gains 2 electron which leads to more repulsion among electron in the valence shell leading to increase in atomic radius of ${\text{O}}^{2-}$.

Conclusion

When silicon is bonded to oxygen it loses 4 electrons so the nuclear pull increases on the valence shell as it becomes ${\text{Si}}^{4+}$, resulting into decrease in its atomic radius. Whereas oxygen gains 2 electron which leads to more repulsion among electron in the valence shell leading to increase in atomic radius of ${\text{O}}^{2-}$.