Question

Write the differences between lanthanoids and actinoids.

Answer 1

Point of Difference	Lanthanoids	Actinoids
Electronic configuration	Involve filling of 4f orbitals.	Involve filling of 5f orbitals.
Oxidation states	Show mainly +3 oxidation state, other states are less common.	Show variable oxidation states (+3 to +6 are common).
Radioactivity	Mostly non-radioactive (except promethium).	All actinoids are radioactive.
Occurrence	More abundant and occur naturally.	Mostly synthetic (except Th, Pa, U).
Chemical reactivity	Less reactive than actinoids.	More reactive, especially in finely divided form.
Complex formation	Less tendency to form complexes.	Greater tendency to form complexes due to higher oxidation states and larger ionic size.

Final Answer:

The main differences are based on orbital filling, oxidation states, radioactivity, occurrence, reactivity, and complex formation. In short: Lanthanoids = 4f series, mostly +3, non-radioactive; Actinoids = 5f series, variable oxidation states, all radioactive.