Chapter 8, Problem 18STP

Interpretation Introduction

Interpretation: The elements that will combine in 2:3 ratios are to be identified.

Concept introduction: The strategy for drawing Lewis structure is mention below.

• Calculate the number of valence electrons present in the molecule.
• Calculate the electron pairs by divding number of valence electrons by 2.
• Determine the bond pairs.
• Determine the lone pairs.
• Check whether the central atom satisfies octet rule.

Answer to Problem 18STP

The elements that will combine in 2:3 ratios are boron and oxygen. Therefore, option (D) is the correct answer.

Explanation of Solution

Reason for correct option: The given electron-dot structure is shown below.

  

The atomic number of boron is five (5). The electronic configuration of boron is $1s^{2}2s^{2}2p^1$ . Here, the number of valence electron in boron is 3. Boron releases these three valence electrons to reach noble gas configuration (chemically stable) and from boron ion $\left({\text{B}}^{3+}\right)$ .

The atomic number of oxygen is eight (8). The electronic configuration of oxygen is $1s^{2}2s^{2}2p^4$ . Here, the number of valence electron in oxygen is 6. Oxygen accepts two electrons to reach noble gas configuration (chemically stable) and from oxygen ion $\left({\text{O}}^{2-}\right)$ .

The charge on boron ion $\left({\text{B}}^{3+}\right)$ is +3 and the charge on oxygen ion $\left({\text{O}}^{2-}\right)$ is -2. To balance the charge, boron ion is multiplied by 2 and oxygen ion is multiplied by 3. Therefore, boron and oxygen combines in ratio of 2:3 to form ${\text{B}}_{\text{2}}{\text{O}}_{\text{3}}$ . Therefore, option (D) is the correct option.