Chapter 7, Problem 17STP

Interpretation Introduction

Interpretation:

The element with seven valence electrons needs to be identified from the given options.

Concept introduction:

The valence electronic configurations of p-block elements can be written as ${\text{ns}}^2{\text{np}}^{1-6}$, here n refers to the elements period and its principal energy level.

Answer to Problem 17STP

E. chlorine has seven valence electrons.

Explanation of Solution

Reason for correct option:

Group 13 to 18 are p-block elements. In p-block elements number of valance electrons is equal to 10 subtracted from their respective group number. Thus, in group 17 the valence electrons will be 7. From the given options only chlorine belongs to group 17. Electronic configuration of chlorine is $\left[\text{Ne}\right]{\text{3s}}^2{\text{3p}}^5$. Thus, E. chlorine has seven valence electrons.

Conclusion

Reason for incorrect option:

1. Valence electron of sodium is 1.
2. Valence electron of chromium 6.
3. Valence electron of boron is 3.
4. Valence electron argon is 8.