Chapter 7.1, Problem 5LC

(a)

Interpretation Introduction

Interpretation: The number of valence electrons present in the potassium atom needs to be determined.

Concept Introduction: The atomic number and electronic configuration of an element also play an important role in determining the number of valence electrons.

Answer to Problem 5LC

The number of valence electrons in potassium is $1$ .

Explanation of Solution

The given atom is potassium. The element belongs to group 1 and the atomic number is 19. The electronic configuration is represented as follows:

  $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^1$

The number of electrons present in the valance shell that is $4s$ is valence electrons. Therefore, the number of valence electrons is equal to 1.

(b)

Interpretation Introduction

Interpretation: The number of valence electrons present in a carbon atom needs to be determined.

Concept Introduction: The atomic number and electronic configuration of an element also play an important role in determining the number of valence electrons.

Answer to Problem 5LC

  $4$

Explanation of Solution

The given atom is carbon. The element belongs to group 14 and the atomic number is 6. The electronic configuration is represented as follows:

  $1s^{2}2s^{2}2p^2$

The number of electrons present in the valance shell,i.e., $2s2p$ is valence electrons. Therefore, the number of valence electrons is equal to 4.

(c)

Interpretation Introduction

Interpretation: The number of valence electrons present in the magnesium atom needs to be determined.

Concept Introduction: The atomic number and electronic configuration of an element also play an important role in determining the number of valence electrons.

Answer to Problem 5LC

The number of valence electrons in magnesium is $2$ .

Explanation of Solution

The given atom is magnesium. The element belongs to group 2 and the atomic number is 12. The electronic configuration is represented as follows:

  $1s^{2}2s^{2}2p^{6}3s^2$

The number of electrons present in the valance shell i.e. $3s$ is valence electrons. Therefore, the number of valence electrons is equal to 2.

(d)

Interpretation Introduction

Interpretation: The number of valence electrons present in an oxygen atom needs to be determined.

Concept Introduction: The atomic number and electronic configuration of an element also play an important role in determining the number of valence electrons.

Answer to Problem 5LC

The number of valence electrons in oxygen is $6$ .

Explanation of Solution

The given atom is oxygen. The element belongs to group 16 or 6A and the atomic number is 8. The electronic configuration is represented as follows:

  $1s^{2}2s^{2}2p^4$

The number of electrons present in the valance shell,i.e., $2s2p$ is valence electrons. Therefore, the number of valence electrons is equal to 6.