Question

What is the general outermost shell electron configuration for Lanthanides?

Answer 1

We know that the lanthanide or lanthanoid arrangement of substance elements contains the fifteen metallic compound components with nuclear numbers$57-71$ , from lanthanum through lutetium. These components, alongside the artificially comparative components scandium and yttrium, are frequently by and large known as the uncommon earth components.

Complete answer:
The components wherein the distinctive electron enters $\left( {n - 2} \right)f$ orbital are f-block components. There are two arrangements of f-block components: Lanthanide (4f - arrangement) and actinides (5f-arrangement).
Lanthanide: has electronic design $\left[ {Xe} \right]4{f^1}^{-14}5{d^{0-1}}6{s^2}$ . It is vigorously good to move a single $5d$ electron to 4f level in the majority of Lanthanoids arrangement with the exception of $Ce,Gd$ and $Lu$. $Gd$ has 5d1 plan because it prompts stable half-filled design and if there should arise an occurrence of $Lu$ to a stable filled f-shell setup.
The casual substance image $Ln$ is utilized in everyday conversations of lanthanide science to allude to any lanthanide. Everything except one of the lanthanides is f-block components, relating to the filling of the $4f$ electron shell. There is some debate on whether lanthanum or lutetium is a d-block component, however lutetium is generally thought about so by the individuals who study the matter; it is incorporated because of its compound likenesses with the other $14$. All lanthanide components structure trivalent cations, $L{n^{3 + }}$ whose science is to a great extent dictated by the ionic sweep, which diminishes consistently from lanthanum to lutetium.
They are called lanthanides on the grounds that the components in the arrangement are synthetically like lanthanum. Since "lanthanide" signifies "like lanthanum", it has been contended that lanthanum can't coherently be a lanthanide; however IUPAC recognizes its consideration dependent on regular use.

Note:
Actinides: There are $14$ elements, after actinium ($Ac$), in which $5f$ orbitals are progressively filled, beginning $Th\left( {90} \right)$ to $Lr\left( {103} \right)$. $Ac$, the d-block component going before the 5f arrangement has an external shell structure$6{d^1}7{s^2}$. For the initial four actinides$Th$ ,$Pa$ ,$U$ and$Np$ , the distinction between the energy level of $5f$ and $6d$ orbital is little. Subsequently in these components electrons may involve either $5d$ or $6f$ orbitals. From $Pu$ onwards, the energy of $5f$ orbital becomes lower and electrons fill the orbitals as if there should arise an occurrence of Lanthanides.