Chapter 7, Problem 19STP

Interpretation Introduction

Interpretation:

The element that has an electronic configuration ${\text{1s}}^{\text{2}}{\text{2s}}^{\text{2}}{\text{2p}}^{\text{6}}{\text{3s}}^2{\text{3p}}^5$ needs to be determined.

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 19STP

E. Chlorine has an electronic configuration of ${\text{1s}}^{\text{2}}{\text{2s}}^{\text{2}}{\text{2p}}^{\text{6}}{\text{3s}}^2{\text{3p}}^5$.

Explanation of Solution

Reason for correct option:

E. Elements of 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. In a neutral atom, number of electrons is equal to number of protons. From the given elements only chlorine belongs to group 17 and electronic configuration of chlorine is ${\text{1s}}^{\text{2}}{\text{2s}}^{\text{2}}{\text{2p}}^{\text{6}}{\text{3s}}^2{\text{3p}}^5$ or $\left[\text{Ne}\right]{\text{3s}}^2{\text{3p}}^5$.

Conclusion

Reason for incorrect option:

Electronic configuration of sodium is $\left[\text{Ne}\right]{\text{3s}}^{\text{1}}$

Electronic configuration of chromium is $\left[\text{Ar}\right]{\text{3d}}^{\text{5}}{\text{4s}}^{\text{1}}$

Electronic configuration of argon is $\left[\text{Ne}\right]{\text{3s}}^2{\text{3p}}^6$

Electronic configuration of chlorine is $\left[\text{Ne}\right]{\text{3s}}^2{\text{3p}}^5$