Question

The inert pair effect is sometimes used to explain the tendency of heavier members of Group 3Ato exhibit +1and +3oxidation states. What does the inert pair effect reference? (Hint: Consider the valence electron configuration for Group 3Aelements.)

Short answer

Due to the inert pair, the effect ${\mathrm{Tl}}^{+}$ is more stable than${\mathrm{Tl}}^{3+}$ whereasrole="math" localid="1663867580615" ${\mathrm{In}}^{3+}$ is more stable than ${\mathrm{In}}^{+}$.

Step-by-step solution

Concept Introduction

The loss of electrons by a molecule, atom, or ion during a process is known as oxidation. When the oxidation state of a molecule, atom, or ion is enhanced, it is called oxidation.

Electrons in an atom's outermost shell are known as valence electrons. The arrangement of electrons around the nucleus of an atom is known as electron configuration.

Inert Pair Effect

Group 3A elements exhibit the inert pair effect.

The inert pair effect is the tendency of the two electrons in the outermost atomic s orbital to remain unshared in compounds of post-transition metals.

As a result, the inert pair of ns electrons remains more tightly held by the nucleus and hence participates less in bond formation.

Because of the inert pair effect, the oxidation states of Group 3A elements determine the chemical properties.

For example,${\mathrm{In}}^{3+}$is more stable than${\mathrm{In}}^{+}$whereas ${\mathrm{Tl}}^{+}$is more stable than ${\mathrm{Tl}}^{3+}$due to inert pair effect as $\mathrm{Tl}$is placed below In in Group 3A and exhibits inert pair effect.

Therefore, ${\mathrm{In}}^{3+}$is more stable than ${\mathrm{In}}^{+}$whereas ${\mathrm{Tl}}^{+}$is more stable than ${\mathrm{Tl}}^{3+}$due to the inert pair effect.