Hint : Lanthanoids and actinoids are elements located in the lanthanide and actinide series of the periodic table. Both the series are included under f− block elements of the periodic table.
Complete answer:
- These elements are identified as f-block because their valence electrons reside in the f orbitals.
- Lanthanoids and actinoids make up a group that is somewhat isolated from the periodic table due to their placement at the bottom.
These are some main differences between lanthanoids and actinoids given below:
| Lanthanide |
Actinoids |
| In lanthanide the filling of 4f orbitals take place. | In action the filling of 5f orbitals take place. |
| This series includes elements from atomic number
57 to 71. |
This series includes elements from atomic number
89 to 103. |
| These elements are non-radioactive except promethium. | All the elements of this series are radioactive. |
| Binding energy of 4f orbitals is higher. | Binding energy of 5f orbitals is higher. |
| Lanthanoids have a low tendency to form complexes. | Actinoids show greater tendency to form complexes. |
| Besides +3 oxidation number it also shows
+2and +4 oxidation state in few compounds. |
Besides +3 oxidation number it also shows
+4,+5 and +7 oxidation state in few compounds. |
| Lanthanoids have a bright and silvery appearance. | Most of the actinides ions are deeply coloured. |
Note: We have discussed some key distinctions between lanthanoids and actinoids above. Both are f-block elements in the periodic table and are soft metals with varying chemical properties. One major difference between the two series is that actinoids readily form complexes, whereas lanthanoids do not form complexes as easily.