Question

Give any two differences between lanthanoids and actinoids.

Answer 1

Hint: Lanthanides and actinides can be differentiated based on which orbital the differentiating electron enters. They can also be differentiated on the basis of binding energy of the orbitals. They also differ in the oxidation states shown by its elements.

Complete step by step answer:
Before writing the differences between lanthanoids and actinoids, let us first understand what they are.
Lanthanoids and actinoids are both series of f-block transition elements. The elements belonging to the lanthanide series and actinide series are placed in separate positions at the bottom of the modern periodic table showing that their general properties and periodicity of electronic structures differ very much from the mainstream elements.

Let us first understand what is meant by a lanthanide. The lanthanide series, also known as lanthanide is a series of 15 chemical elements with the atomic numbers: 57-71.
i) Lanthanides are represented by the chemical symbol – Ln.
ii) Lutetium, Lanthanum, Promethium are some of the examples of lanthanides.

Now, let us have a look at the actinide series. The actinide series is also known as actinide. It is a series of 15 metallic chemical elements with the atomic numbers: 89-103.
i) Actinides are represented by the chemical symbol – An.
ii) Thorium, Uranium, Curium are some of the examples of actinides.

Before looking at the differences between lanthanoid and actinoid series, let us look at the similarities.
Both lanthanides and actinides have a prominent oxidation state of +3, and are involved in the filling of (n-2) f orbitals. Both are highly reactive and electropositive.
 Let us now look at the differences between lanthanoid and actinoid series.

Lanthanides	Actinides
The differentiating electron enters the 4f orbital.	The differentiating electron enters the 5f orbital.
They belong to the sixth period of the periodic table	They belong to the seventh period of the periodic table.
The binding energy of 4f orbitals is higher than that of 5f orbitals.	The binding energy of 5f orbitals is lower than that of 4f orbitals.
Lanthanides show less tendency to form complexes.	Actinides show greater tendency to form complexes.
+2 and +4 are the oxidation states seen besides +3.	+4, +5 , +7 higher oxidation states are the oxidation states seen besides +3.
Promethium is the only radioactive element in the lanthanide series.	All actinides are radioactive.

Note: The lanthanoid and actinoid series cannot be found on the main part of the periodic table. They are placed at the bottom of the periodic table as they differ in general properties and periodicity of electronic structures from the mainstream elements.