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Comparison between Main and Inner transition elements

Main transition elements are the elements of the d-block, occupying three horizontal periods (fourth, fifth, and sixth). Their energy levels are completely filled with electrons except the outer two energy levels. The d-sublevels of these elements are successively filled. Examples include Iron, Copper, and Manganese.

Inner transition elements are the elements of the f-block, occupying two horizontal series (lanthanides and actinides). Their energy levels are completely filled with electrons except the outer three energy levels. The f-sublevels of these elements are successively filled. Examples include Uranium and Cerium.

Comparison between Main and Inner transition elements
Main transition elements
The elements of d-block
They occupy three horizontal periods
(fourth, fifth and sixth)
Their energy levels are completely
filled with electrons except the outer
two energy levels
d-sublevels of these elements are
successively filled
Ex: Iron - Copper - Manganese
Inner transition elements
The elements of f-block
They occupy two horizontal series
(lanthanides - actinides)
Their energy levels are completely
filled with electrons except the outer
three energy levels
f-sublevels of these elements are
successively filled
Ex: Uranium - Cerium
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