Transition and Inner Transition Elements — Chemistry STD 12 Science — Question

The elements in which the differentiating electron (last electron) enters (n-2) f orbital are known as f-block elements. The differentiating electron enters the pre-penultimate shell. The f-block elements are the lanthanides and actinides and are also called inner transition elements. All 28 elements from atomic numbers 58 to 71 and from atomic numbers 90 to 103 are collectively called f-block elements.

Lanthanoids	Actinoids
Differentiating electron enters 4f orbitals	Differentiating electron enters 5f orbitals
Belong to the sixth period and form part of the third transition series. They constitute the first inner transition series.	Belong to the seventh period and form part of the fourth transition series. They constitute the second inner transition series.
Binding energy of 4f orbitals is higher.	Binding energy of 5f orbitals is lower.
Besides the +3 oxidation state, lanthanoids show +2 and + 4 oxidation states in few cases.	Besides the +3 oxidation state, actinoids show higher oxidation states such as +4, +5 and +7.
They show lesser tendency to form complexes.	They show greater tendency to form complexes.
Some of the lanthanoids are fairly coloured.	Most of the ions of actinoids are deeply coloured. Examples: U3+ (red), U4+ (green)
Only promethium is radioactive.	All the members of this series are radioactive.