Briefly explain why electronic conflguration of lanthanoids are not known with certainty ?

Cu+2 = [Ar] 3d9 4s0 Co+2 = [Ar] 3d7

In the lanthanide series, +3 oxidation state is most common i.e., Ln(III) compounds are predominant. However, +2 and +4 oxidation states can also be found in the solution or in...

(i) Electronic configuration The general electronic configuration for lanthanoids is [Xe]54 4f0-14 5d0-1 6s2 and that for actinoids is [Rn]86 5f1-14 6d0-1 7s2. Unlike 4f orbitals, 5f orbitals are not deeply...

Lanthanoids primarily show three oxidation states (+2, +3, +4). Among these oxidation states, +3 state is the most common. Lanthanoids display a limited number of oxidation states because the energy difference...

Electronic configuration The general electronic configuration for lanthanoids is [Xe]54 4f0-14 5d0-1 6s2 and that for actinoids is [Rn]86 5f1-14 6d0-1 7s2. Unlike 4f orbitals, 5f orbitals are not deeply buried...

Lanthanoids show limited number of oxidation state, viz., +2, +3 and +4 (out of which +3 is most common). This is because of large energy gap between 4f and 5d-subshells....

(c) :- +4 oxidation state of cerium is also known in solutions.

Characteristics Lanthanoids Actinoids (i) Electronic configuration   [Xe] 4f 1-145d0-16s2 [Rn] 5f 1-14 6d0-17s2 (ii) Oxidation states                    Besides + 3 O.S. lanthanoids show +2 and +3 O.S. only in a few...

(d) : Availability of 4f electrons does not result in the formation of compounds in +4 state for all the members of the series.