Chapter 6, Problem 85A

Interpretation Introduction

Interpretation: The element with largest ionization energy from platinum or cobalt needs to be determined.

Concept Introduction: Ionization energy is the amount of energy required to remove an outermost electron from the atom.

The factors that influence the ionization energy are:

1. The size of the atom
2. The charge on the nucleus
3. The type of electrons involved (s, p, d and f)

Answer to Problem 85A

Ionization energy of cobalt is higher than Platinum.

Explanation of Solution

The electronic configuration of cobalt is as follows:

  $\left[\text{Ar}\right]{\text{4s}}^{\text{2}}{\text{3d}}^{\text{7}}$

Electronic configuration of Platinum is as follows:

  $\left[\text{Xe}\right]{\text{4f}}^{14}{\text{5d}}^{9}6{\text{s}}^1$

The last electron of cobalt exits in 4s sub-shell, while last electron of platinum exits in 6s sub-shell. The valence electrons of Co are closer than the valence electrons of Pt. So, Co need more energy to remove electrons from there outer shell. Therefore, ionization energy of cobalt is higher than Platinum.

Conclusion

In the periodic table, ionization energy increases as left to right in a period and decreases down the group.