8.30 Compare the chemistry of actinoids with that of the lanthanoids with special reference to: 

(i) Electronic configuration

(ii) Atomic and ionic sizes

(iii) Oxidation state

(iv) Chemical reactivity.

Lanthanoids

Actinoids

Electronic Configuration

It is represented by [Xe]4f^x5d^y6s^2, where x varies from 0 to 14 and y= 0 or 1

It is represented by [Rn]5f^x6d^y7s², where x varies from 0 to 14 and y= 0

or 1.

Oxidation state

Generally shows +3 oxidation state only in some cases it is +2 or +4 but never greater than +4

It has +3 oxidation state but also shows higher oxidation states such as +4, +5, +6, +7.

Atomic and ionic sizes

Ionic radii of M³⁺ions decrease in size with increase in atomic number this is called as lanthanoid contraction.

There is a gradual decrease in the size of M³⁺ ions across the series, this is known as actinoid contraction.

Chemical Reactivity

Lanthanoids are less reactive in nature and form oxides, sulphides, nitrides etc. They have a lesser tendency to form complexes.

They are highly reactive in nature when they are in the finely divided state. They have a higher tendency to form complexes and even react with non-metals at moderate temperature.