Chapter 8, Problem 9STP

Interpretation Introduction

Interpretation:

The compound that does not have a bent shape is to be identified.

Concept introduction:

The molecular shape of a molecule is determined via a model referred as valence shell electron pair repulsion (VSEPR) model. According to this model, in a molecule, the atoms and the lone pairs around the central atom are arranged in such a manner that minimizes the repulsion.

Answer to Problem 9STP

The compound that does not have a bent shape is ${\text{BeH}}_{\text{2}}$. Therefore, option (A) is the correct option.

Explanation of Solution

Reason for correct option: The atomic number of beryllium and hydrogen is 4 and 1 respectively. The electronic configuration is written below.

$\begin{array}{c}{\text{Be}}_{\text{4}}=1s^{2}2s^2\\ {\text{H}}_{\text{1}}=1s^1\end{array}$

The bonding in ${\text{BeH}}_{\text{2}}$ is shown below.

Therefore, each hydrogen atom is attached with beryllium atom via single bond. There is no lone pair of electrons. Therefore, the shape of ${\text{BeH}}_{\text{2}}$ is linear with $180°$ bond angle as shown below.

Therefore, correct option is option (A).

Conclusion

Reason for incorrect option: The compound ${\text{H}}_{\text{2}}\text{O}$ has bent shape. So, B is incorrect option.

The compound ${\text{H}}_{\text{2}}\text{S}$ has bent shape. So, C is incorrect option.

The compound ${\text{SeH}}_{\text{2}}$ has bent shape. So, D is incorrect option.