Question

What are $f$-block elements ? Distinguish between lanthanoid and actinoid.

Answer 1

$f$-block elements : The elements of which differentiating electron enters into $(n-2)f$ orbital or $d$-orbital of penultimate shell or $d$-orbital of antepenultimate shell are called as $f$-block elements.
Distinguish between lanthanoides and actinoides.

Lanthanoid	Actinoids
1. Differentiating electron enters in $4-f$ orbital	1. Differentiating electron enters in $5-f$ orbital.
2. Belongs to 6th period and form a part of third transition series.	2. Belong to 7th period and form a part of third transition series.
3. Binding energy of $4-f$ orbital is higher.	3. Binding energy of $4-f$ orbital is lower.
4. Only Promethium is radioactive.	4. All members are radioactive.
5. Beside $+3$ oxidation state lanthanoids shows $+2$ and $+4$ oxidation states in few cases.	5. Beside $+3$ oxidation state actinoids shows $+4$, $+5$, $+7$ higher oxidation states also.
6. Lanthanoids show low tendency to form complexes.	6. Actinoids show greater tendency to form complexes.
7. Some of the ions of lanthanoids are fairely coloured.	7. Most of the ions of actinoids are fairely coloured.
8. Lanthanoid hydroxides are less basic in nature.	8. Actinoid hydroxides are more basic in nature.
9. Contraction is relatively less.	9. Contraction is greater.