Question
Write four points of distinction between Lanthanoids and Actinoids.

Answer

LanthanoidsActinoids
1In lanthanoids, last differentiating electron occupies 4f orbital.In actinoids, last differentiating electron occupies
5f orbital.
2They are the elements of first inner transition series.They are the elements of second inner transition series
3They are present in period 6 .They are present in period 7 .
4Most of lanthanoids (with exception of
promethium) occur in nature.
Most of actinoids (with exception of uranium and
thorium) are prepared in laboratory
5Most of lanthanoids (with exception of
promethium) are non-radioactive.
All the actinoids are radioactive.
6Lanthanoids do not form oxo cation.Actinoids form oxo cation such as 22 UO_(2)^(2+),PuO^(2+),UO^(+).
74 f orbitals in lanthanoids have higher
binding energy.
5f orbitals in actinoids have lower binding energy.
8Contraction in atomic and ionic radii is relatively less in lanthanoids.Contraction in atomic and ionic radii is relatively
greater in actinoids due to poor shielding of 5f
electrons.
9Lanthanoids show +2,+3 and +4 oxidation states.Actinoids show +3,+4,+5,+6,+7 oxidation
states.
10Lanthanoids have less tendency to form complexes.Actinoids have greater tendency to form
complexes.
11Some ions of lanthanoids are coloured.Most of the ions of actinoids are deeply coloured.
12Lanthanoid hydroxides are less basic in nature.Actinoid hydroxides are more basic in nature.

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