Question

Give the general electronic configuration of lanthanides and actinides?

Answer 1

Hint: A block of the periodic table is a group of elements linked together by the orbitals in which their valence electrons or vacancies are located. The \[s\] block, \[p\] block, \[d\] block, and \[f\] block are all named after their respective orbitals.

Complete answer:
The elements of the \[f\] block are divided into two groups: lanthanoids and actinoids. These elements are known as inner transition metals because they provide a transition between the \[s\] and \[d\] blocks of the periodic table in the \[{6^{th}}\] and \[{7^{th}}\] rows.
\[f\] block elements have electrons attached to the \[f\] sub-orbitals of the \[\left( {n - 2} \right)\] level, electrons are located between \[\left( {n - 1} \right)d\] and \[ns\] block elements in the periodic table, and their properties are identical to those of \[d\] block elements.
From lanthanum to lutetium, the lanthanide or lanthanoid sequence of chemical elements consists of \[15\] metallic chemical elements with atomic numbers \[57 - 71\] . Rare-earth elements are a group of elements that includes these and the chemically related elements scandium and yttrium.
Actinium through lawrencium is the \[15\] metallic chemical elements in the actinide sequence, with atomic numbers ranging from \[89 - 103\] . The first element in the sequence, actinium, gives the actinide series its name. In general discussions of actinide chemistry, the informal chemical symbol \[An\] is used to refer to any actinoid.
The general electronic configuration is given as,
Lanthanides : \[\left[ {Xe} \right]4{f^{1 - 14}}5{d^{0 - 1}}6{s^2}\]
Actinides : \[\left[ {Rn} \right]5{f^{0 - 14}}6{d^{0 - 2}}7{s^2}\]

Additional Information:
Except for promethium, all lanthanides are non-radioactive, whereas all actinide sequence elements are radioactive.
While lanthanides do not appear to form oxo-cations, the actinide sequence has many oxo-cations. The compounds formed by lanthanides are less basic than those formed by actinides, which are extremely basic.

Note:
The elements of the \[f\] block are mentioned separately at the bottom of the periodic table. They are a combination of the \[{6^{th}}\] and \[{7^{th}}\] periods.