What are the example of inner transition element?

Answer 1

The inner transitional metals contain 2 main groups, the lanthanide series, and the actinide series (f block elements).

The lanthanide series include the 14 elements that proceed lanthanum (atomic number 57) from atomic numbers 58 to 71. Their electron configuration include the 4f and 5d energy levels. Because of the closeness of those two levels, there is considerable uncertainty in some electron configuration assignments.

The actinide series include the 14 elements that proceed actinium (atomic number 89) from atomic numbers 90 to 103. The electron configurations of the actinides are even more uncertain than the lanthanides because the closeness of the energy levels and because the nuclei are unstable to radioactive decay. Only minute amounts of some elements are obtained because of their instability. All of the actinides are unstable with respect to alpha emission. The later members tend to undergo spontaneous fission, a fact which limits the number of elements possible.