Tag: comparison of lanthanoids and actinoids

Questions Related to comparison of lanthanoids and actinoids

More number of oxidation states are exhibited by the actinoids than by lanthanoids. The main reason for this is:

chemistry d- and f-block elements comparison of lanthanoids and actinoids actinoids the actinoids

  1. greater metallic character of the lanthanoids than that of the corresponding actinoids.

  2. more active nature of the actinoids.

  3. more energy difference $5f$ and $6d$-orbitals than that between $4f$ and $5d$-orbitals.

  4. lesser energy difference between $5f$ and $6d$-orbitals than that between $4f$ and $5d$-orbitals.

Show answer
Correct Option: D
Explanation:

Actinoids display more oxidation states because of very small energy gap between 5f, 6d and 7s sub shells. Thus, the outermost electrons get easily excited to the  higher energy level giving variable oxidation state.

Hence,option D is correct.
 

Statement 1: Lanthanides have much less tendency to form complexes than actinides.
Statement 2: Compared to actinides, the lanthanides have relatively larger size of atoms and less nuclear charge.

chemistry d- and f-block elements comparison of lanthanoids and actinoids actinoids the actinoids

  1. Statement 1 is True, statement 2 is True, statement 2 is a correct explanation of statement 1.

  2. Statement 1 is True, statement 2 is True, statement 2 is not a correct explanation of statement 1.

  3. Statement 1 is true, Statement 2 is False.

  4. Statement 1 is False, Statement 2 is True.

Show answer
Correct Option: A
Explanation:

Because of higher effective nuclear charge and smaller size of atoms the actinides have higher charge density and because of that they have greater tendency to form complexes than the lanthanides.

The main reason for larger number of oxidation states exhibited by the actinoids than the corresponding lanthanoids, is:

chemistry d- and f-block elements comparison of lanthanoids and actinoids actinoids the actinoids

  1. the lesser energy difference between 5f and 6d orbitals than between 4f and 5d orbitals

  2. more energy difference between 5f and 6d orbitals than between 4f and 5d orbitals

  3. greater reactive nature of the actinoids than the lanthanoids

  4. larger atomic size of actinoids than the lanthanoids

Show answer
Correct Option: A
Explanation:

Actinoids shows larger oxidation states due to poor shielding of both $4f$ and $5f$ orbital electrons as a result these orbital have almost similar energy and hence take part in bond formation. Also, there is very small energy between $5f, 6d$ and $7s$ subshells.

The number of oxidation states is exhibited by the actinoids more than by the lanthanide. The main reason for this is:

chemistry d- and f-block elements comparison of lanthanoids and actinoids actinoids the actinoids

  1. more energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals.

  2. the lesser energy difference between 5f and 6d orbitals than between 4f and 5d orbitals.

  3. the greater metallic character of the lanthanoids than that of the corresponding actinoids.

  4. more active nature of the actinoids.

Show answer
Correct Option: B
Explanation:

Actinides show larger oxidation states due to poor shielding of both $4f$ and $5f$ orbital electrons, as a result, their orbitals have almost similar energy and hence take part in bond formation. Thus the energy gap between $5f, 6d$ and $7s$ become very small.