Chapter 2, Problem 2A.9E

(a)

Interpretation Introduction

Interpretation:

The ${\text{M}}^{2+}$ ion that is expected to have electronic configuration of $\left[\text{Ar}\right]{\text{3d}}^7$ has to be predicted.

Concept Introduction:

The fundamental principles that are followed to write an electronic configuration include three rules as follows:

Electron in a $s$ orbital is relatively low in energy than a ${\text{p}}_{\text{x}}$ electron because the $s$ orbital is in nearer vicinity of nucleus than ${\text{p}}_{\text{x}}$ orbital. This is basis of Aufbau rule that suggests electrons occupy orbitals in order so that lowest energy orbital gets filled first. For instance the order is illustrated as follows:

Hund’s rule suggests electrons are not allowed to be paired up until each degenerate set of orbital has got at least one electron.

Pauli Exclusion Principle states two electrons within the same orbital cannot possess same set for four possible quantum numbers. Quantum-mechanical equivalent for this state means that two electrons are not allowed to have the same space simultaneously. Since one electron may certain discrete same set of n, l and m values, however, the fourth spin quantum number should be different. This provides a unique address to every electron. Since the possible magnitudes of spin can be either +1/2 or -1/2 thus at maximum two electrons can occupy any given orbital.

The convention followed to remove or add electrons is electrons of largest principal quantum number are lost first. In case of subshells of the same $\text{n}$ value, electrons are lost from the subshell with highest $\text{l}$ value. In case of d-block elements, the $\text{ns}$ electrons are removed prior to $\left(\text{n}-1\right)\text{d}$ electrons.

(b)

Interpretation Introduction

Interpretation:

The ${\text{M}}^{2+}$ ion that is expected to have electronic configuration of $\left[\text{Ar}\right]{\text{3d}}^6$ has to be predicted.

Concept Introduction:

Refer to part (a).

(c)

Interpretation Introduction

Interpretation:

The ${\text{M}}^{2+}$ ion that is expected to have electronic configuration of $\left[\text{Kr}\right]{\text{4d}}^4$ has to be predicted.

Concept Introduction:

Refer to part (a).

(d)

Interpretation Introduction

Interpretation:

The ${\text{M}}^{2+}$ ion that is expected to have electronic configuration of $\left[\text{Kr}\right]{\text{4d}}^3$ has to be predicted.

Concept Introduction:

Refer to part (a).