Chapter 17, Problem 109A

Interpretation Introduction

Interpretation: The elements are to be arranged in order of increasing atomic radius.

Concept introduction: Atomic radius is the total distance from the center of the nuclei to the outermost shell which contains the electron.

Atomic radius decreases as we move across a period and atomic radius increases as we move down a group.

Answer to Problem 109A

The order of the increasing atomic radius will be: Germanium >Arsenic > Phosphorous

Explanation of Solution

As we move across a period, the atomic number of the element increases but the electron gets added up in the same valence shell thus the effective nuclear charge gets increased and the valence electron gets more attracted toward the nucleus, decreasing the atomic radius.

However, on moving down a group, the atomic number of the element increases but now the electrons are added in new shells and thus effective nuclear charge decreases leading to an increase in atomic radius.

As Arsenic (As) lies below phosphorous (P) in the same group, thus Arsenic has a larger atomic radius than phosphorous (P). Germanium (Ge) lies to the left of Arsenic (As), thus, the atomic radius of Germanium (Ge) is larger than that of Arsenic (As).

Conclusion

Thus, the order of the increasing atomic radius will be Germanium >Arsenic > Phosphorous