The pair of lanthanides will exceptionally high 3^rd ionisation enthalpy than neighbouring elements:

Question

Statement-I : Consider the following pairs of ions $(\text{Sc}^{3+}, \text{Ti}^{3+}), (\text{Ti}^{4+}, \text{Ni}^{2+}), (\text{Cu}^{2+}, \text{Zn}^{2+})$ and $(\text{Cr}^{3+}, \text{Mn}^{3+})$. Out of these pairs three pairs consist of ions that are both coloured :
Statement-II : Among the lanthanide ions $\text{Eu}^{2+}$, $\text{Gd}^{3+}$, $\text{Ce}^{4+}$ and $\text{Tb}^{4+}$, the ion $\text{Tb}^{4+}$ is the strongest reducing agent.
Choose the correct option.

Answer 1

The question asks about the pair of lanthanides with exceptionally high third ionization enthalpy compared to neighboring elements. Let's analyze the provided options to arrive at the correct answer.

To understand this, we need to consider the electronic configurations of lanthanides. Lanthanides are elements with atomic numbers ranging from 57 (Lanthanum) to 71 (Lutetium). Key factors affecting ionization enthalpy are electronic configuration, particularly the stability associated with half-filled or fully filled subshells.

In lanthanides, the subshell of interest is 4f. Ionization enthalpy generally increases when a stable electronic configuration is disrupted. Notably, elements with half-filled (f⁷) or fully filled (f¹⁴) subshells exhibit higher ionization enthalpies.

Europium (Eu, Z = 63): The electronic configuration of Eu is [Xe] 4f⁷ 6s². It has a half-filled 4f subshell, providing extra stability and resulting in a higher third ionization enthalpy.
Ytterbium (Yb, Z = 70): The electronic configuration of Yb is [Xe] 4f¹⁴ 6s². It has a completely filled 4f subshell, again providing extra stability and leading to high third ionization enthalpy.

Analyzing the other options:

Lutetium (Lu): [Xe] 4f¹⁴ 5d¹ 6s². Though Lu also has a stable configuration owing to a completely filled 4f shell, it is the third ionization enthalpy that stands out for Eu and Yb.
Dysprosium (Dy): [Xe] 4f¹⁰ 6s². It does not have a half-filled or fully filled 4f subshell.
Gadolinium (Gd): [Xe] 4f⁷ 5d¹ 6s². While Gd also has a half-filled configuration (after the removal of three electrons), the pairing with Yb is more exceptional.

Therefore, the pairing of Eu with Yb is the only one with unique stability characteristics due to half-filled and fully filled 4f shells, respectively, resulting in exceptionally high third ionization enthalpy.

Correct Answer: Eu and Yb

Answer 2

The question asks about the pair of lanthanides with exceptionally high third ionization enthalpy compared to neighboring elements. Let's analyze the provided options to arrive at the correct answer.

To understand this, we need to consider the electronic configurations of lanthanides. Lanthanides are elements with atomic numbers ranging from 57 (Lanthanum) to 71 (Lutetium). Key factors affecting ionization enthalpy are electronic configuration, particularly the stability associated with half-filled or fully filled subshells.

In lanthanides, the subshell of interest is 4f. Ionization enthalpy generally increases when a stable electronic configuration is disrupted. Notably, elements with half-filled (f⁷) or fully filled (f¹⁴) subshells exhibit higher ionization enthalpies.

Europium (Eu, Z = 63): The electronic configuration of Eu is [Xe] 4f⁷ 6s². It has a half-filled 4f subshell, providing extra stability and resulting in a higher third ionization enthalpy.
Ytterbium (Yb, Z = 70): The electronic configuration of Yb is [Xe] 4f¹⁴ 6s². It has a completely filled 4f subshell, again providing extra stability and leading to high third ionization enthalpy.

Analyzing the other options:

Lutetium (Lu): [Xe] 4f¹⁴ 5d¹ 6s². Though Lu also has a stable configuration owing to a completely filled 4f shell, it is the third ionization enthalpy that stands out for Eu and Yb.
Dysprosium (Dy): [Xe] 4f¹⁰ 6s². It does not have a half-filled or fully filled 4f subshell.
Gadolinium (Gd): [Xe] 4f⁷ 5d¹ 6s². While Gd also has a half-filled configuration (after the removal of three electrons), the pairing with Yb is more exceptional.

Therefore, the pairing of Eu with Yb is the only one with unique stability characteristics due to half-filled and fully filled 4f shells, respectively, resulting in exceptionally high third ionization enthalpy.

Correct Answer: Eu and Yb

The pair of lanthanides will exceptionally high 3^rd ionisation enthalpy than neighbouring elements:

The Correct Option is C

Solution and Explanation

Top Questions on d -and f -Block Elements

Questions Asked in JEE Main exam

The pair of lanthanides will exceptionally high 3rd ionisation enthalpy than neighbouring elements:

The Correct Option is C

Solution and Explanation

Top Questions on d -and f -Block Elements

Questions Asked in JEE Main exam

The pair of lanthanides will exceptionally high 3^rd ionisation enthalpy than neighbouring elements: