D And F Block Elements

Step 1: Understanding inner transition elements.
Inner transition elements are the elements that are found in the lanthanide and actinide series. These elements have their f-orbitals being filled.

Step 2: Identifying the element.
Among the given options, Cerium (Ce) is an inner transition element, as it belongs to the lanthanide series.

Step 3: Conclusion.
The correct answer is Ce, which corresponds to option (4).

Step 1: Electronic configuration of Scandium.
Scandium (atomic number 21) has the following electronic configuration:

Step 2: Conclusion.
The electronic configuration of Scandium is .

Step 1: Difference between d-block and f-block elements.
1. d-block elements are also known as transition elements, and they are found in groups 3 to 12 of the periodic table. f-block elements are the lanthanides and actinides, and they are placed in the two rows below the main body of the periodic table.
2. d-block elements have incomplete d-orbitals in their valence shell, while f-block elements have incomplete f-orbitals.
3. d-block elements generally exhibit multiple oxidation states, whereas f-block elements mostly show a fixed oxidation state, either +3 or +2 in the case of lanthanides.

Step 2: Conclusion.
Thus, the d-block and f-block elements differ in their position, electron configuration, and oxidation states.

Step 1: Difference between Lanthanoid and Actinoid.
1. Lanthanoids are the 15 elements with atomic numbers 57 to 71, from Lanthanum (La) to Lutetium (Lu), and are also known as the rare earth elements. Actinoids, on the other hand, are the 15 elements with atomic numbers 89 to 103, from Actinium (Ac) to Lawrencium (Lr).
2. Lanthanoids are less radioactive compared to Actinoids, and many of the actinoids are highly radioactive, with elements like Uranium and Thorium being used as nuclear fuel.
3. Lanthanoids generally exhibit a +3 oxidation state, while Actinoids can exhibit a wider range of oxidation states, including +3, +4, and even +5.

Step 2: Conclusion.
The lanthanoids and actinoids differ in their atomic number range, radioactivity, and oxidation states.