Lanthanoid Contraction Video Lecture | Chemistry for JEE Main & Advanced

in chemistry concepts today we will talk
about lanthanide and actinide
contraction and before I start with
length in a delicate contraction first
of all let me tell you something about
the variation of atomic radii in B block
elements there are 3 3 3 d 4 D 5 D and
in all of the 3 each of the 3 series
what happens that atomic size first
decreases till the middle and then the
decrease becomes less and in the end it
increases so the reason behind this is
the shielding effect of B orbitals in
the starting electronic contribution is
B 0 or they're only 1 2 3 or 4 D
electrons and the lesser the number of D
electrons weaker would be the shielding
effect of D orbitals and now in F n D
orbitals and so n minus 1 D orbitals are
not able to shield outer s al
curvalicious electrons and because of
which the size decreases more rapidly
than expected but when we move when we
reach to the middle the number of
electrons are 5 its half filled and
nowadays considerable amount of
shielding effect and it shields well and
then the size does not make it so fast
and in the end infected increases with D
10 so basically what I'm saying that
whether it is 3d folder of a 5d series
the atomic size first decreases atom in
the N is little bit increase that means
not a sharp decrease the removal on the
period but in case of lambda reuters
economics this trend which is observed
in transition element the size will
first this trend which is observed that
the size will first decrease and then
increase is not observed in case of
lanthanides and actinides Esha
whereas sighs sharply keeps on
decreasing it does not increase and this
is the curse in length annoyed
its x4f in economics 5f electrons which
are present in the shilling of
these F orbitals are too too weak so
it's a sudden decrease and there is no
increase and because of this reason we
cannot put the transit the length and
electrolyte in the main periodic table
we have to put them separately so what
is lanthanide contraction lanthanide
construction is actually sharp decrease
in the Tomic radii when we move along
the series
similarly actinide contraction is also
the sharp decrease in the atomic read a
when we move along the actinide series
and this is because of the weak
shielding effect of F electrons involved
and this is the reason because of which
the zirconium one one of the reason is
that zirconium and hafnium have almost
similar size one is of foldy another is
of five basically the ford e-series and
5d series elements are almost similar
size and this is because of this
lanthanide contraction please don't
forget to subscribe and stay tuned for
more videos of organic inorganic and
physical chemistry
[Music]