Question

The common oxidation state of elements of lanthanide series is:
(i) +1
(ii) +3
(iii) +4
(iv) +6

Answer 1

Hint: An element gains or loses electrons from its outermost shell in order to gain stability. Therefore, all compounds have a stable oxidation state. Lanthanides are rare earth metals present in the 4f series of the periodic table.

Complete step by step answer:
Lanthanides refers to 14 metallic elements present in f-block with atomic numbers ranging from 58-71.
The general electronic configuration of lanthanides is \[4{{f}^{1-14}}5{{d}^{0-1}}6{{s}^{2}}\]. The last electron always enters into the 4f orbital (Aufbau principle).
All lanthanides show an oxidation state of +3. It also shows an oxidation state of +2 and +4 in complexes, but +3 is the most stable. While oxidation, electrons are removed from 6s (2 electrons) and 4f orbital (1 electron). A big energy difference lies between 6s and 4f orbital. Being closer to the nucleus, 4f doesn’t lose electrons as easily.
Therefore, the answer is – option (b) – The common oxidation state of elements of lanthanide series is +3.

Additional Information:
Electrons are filled in an atom according to the Aufbau principle. It states that “in the ground state of an atom or ion, electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels”.

Note: Inner transition metals are those elements which are placed in two rows below the main table in the modern periodic table. They are also known as the f-block of the periodic table. It includes – actinides and lanthanides.