Question

Discuss the electronic configuration of lanthanide and actinide compare their oxidation and ionic radii

Answer 1

Answer:

 (i) Electronic configuration

lanthanoids have general electronic configuration [Xe]4f1−145d0−16s2. Actinoids have general electronic configuration [Rn]5f1−146d0−17s2. 

In lanthanoids, 4f orbital is filled and in actinoids, 5f orbital is filled.

(ii) Atomic and ionic sizes

The atomic and ionic sizes of lanthanoids and actinoids decrease with increase in the atomic number due to lanthanoid and actinoid contraction.

(iii) Oxidation state

Apart from +3 oxidation state, lanthanoids show +2 and +4 oxidation states due to large energy gap between 4f and 5d subshells. Whereas actinoids show large number of oxidation states due to small energy gap between 5f and 6d subshells.

(iv) Chemical reactivity

Highly electropositive lanthanoids have almost similar chemical reactivity. Actinoids (electropostive and highly reactive) are more reactive (specially in finely divided state) than lanthanoids.