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advanced videos Hello Friends now we are
going to talk about the next periodic 
that is shielding it and let us talk
about its strength in predictable also
so let us go
so let us understand what is actually
screening or shielding effect the inner
shell electrons in an atom screen or
shield the outermost valence electrons
so this is true that is the inner shell
electrons in an atom actually shape or
prevent the outermost electron from the
attraction of the nucleus to the
interaction of the nucleus from the
nuclear attraction this effect is known
as DC shielding effect or skimming
effect this is what I have explained a
railroad but let me explain it again for
example if you have a key about an atom
it should consist of a nucleus and
various shells as you can see so this
shell would consist of electrons as we
know this will consist of medius
electrons so for instance I am
destroying four levels in the second
shell but actually it is the maximum
limit that it could contain electronic
state so in this thing suppose if I have
a dog and I'm coming this way so what is
actually shaking if it
Schilling in front will be nothing but
the inner electrons or the inner
electrons which are present in the inner
shell as you can see this is the upper
motion and the electrons are said to be
the outermost electrons while these are
the inner shell or the innermost shells
so what happens is because of this
either electrons that are present very
close to that of the nouvlesse what will
happen because of which the nuclear
charge will go on increasing towards
this electrons and because of which the
attraction of this inner electrons will
be more in case when we are talking
about the inner electrons so what
happens is if the number of electron
increases and moreover if we see that we
are talking about the already is like s
P D and M so it is been observed that
the S orbitals have basically more
shooting effect than compared to the P
compared to B and compared to F so the
PDA charge is nothing but the force of
attraction between the nucleus and the
outermost electrons as you can see that
this R
later on so they should have attraction
with this nucleus so that should be an
attraction with this nucleus so
therefore this is known as basically in
pleasure but this nuclear charge can
reduce or it can decrease also it
depends on basically the inner electrons
as you could see so it depends on the
inner electrons and inner electrons
plays a very vital boon as you could see
here this inner electrons is very vital
doses because the more the number
electrons in the inner shell so they
will try to protect the nucleus so as to
attack the outermost electrons so this
kind of protection all that we could see
that this kind of screening where the
nucleus is not been allowed to attack
towards the optimist electron so this
kind of screening is where this kind of
effect that is shown by the inner
orbitals or the urchins when we are
talking about the inner electrons so
this kind of dimension all this kind of
screening is basically known as
shielding effect so therefore because of
which the nuclear charge will not be
more in case of the outermost electron
so this is this is known as screening
effect so now let us talk about the so
now let us talking about the what would
be the trend if we observe in periodic
table the time that we are talking about
that is in periods and in groups so
there will be two discussion that be
able to do that is the first one is in
periods so what kind of variation that
we could observe when we observe a
period in a periodic table the first
thing that we observe in the when we go
through a period of an periodic table
and year period and consult with the we
are in concerned with the screening
effect and that is the first point that
we are going to discuss as we move from
left to right what happens is
atomic number increases and that
increase will be gradual so first of all
the atomic number increases gradually
and the second point that we are going
to discuss about that is the electron
that enters in the outer V Automotion
will be in the same shell itself for
example when we are talking about the
period then the electrons are entering
the new electrons are mentally in the
same shape for example if I would say
for saline or sudden we have the
Automotion known as 3s and that 3s will
consist of money later on but when we
are talking about magnesium magnesium
has an atomic number of 2l which means
that it consists of 12 electrons so this
extra later all this this twelfth
electron this will enter in the large
shell that is 3s shell only or 3 s
subshell moon so because every time we
will add an electron in the period so
that electron will add in the same main
sub shell so that is the reason what
happens is because of the electrons that
are been increasing in the same sub
shell or in the same main shell because
of which the NA the atomic number
increases as you could say then the
nuclear charge will also increase so the
second point that we are going to see it
as the electron enters in the same
maintian the new electron that is we are
talking about the new electron million
to in the same region and move people
observe this we could observe that the
nuclear charge will go on increasing
because if the number of electrons are
being on the same shell and that chain
is nothing but we optimal shell as we
could observe so that usually the
outermost shell will have more
attraction towards the nucleus and
because of which whatever the email
electrons will remain constant
throughout that thing and because of
which the nuclear charge will increase
there is nuclear charge increase and
because of what we could observe that
the screening effect is less and because
of which because the nuclear charge is
increasing that it obviously it means
that when it comes to period when we are
talking about period then the screening
effect the skimming in fact actually it
decreases it decreases and hence the
reason what happens because of the
negative charge is increasing and
moreover we could say that the screaming
effect is less or it decreases denser
reason the atomic size goes on
decreasing when we are talking about
when we are in concerned with the
screening effect in terms of periods so
now let us talk about what will happen
when we are I am concerned with further
10 in good so now what happens in blue
picture is a as we move up to know what
we could observe is that the atomic
number goes on increasing but that
increase is very much rapid this is what
we have explained earlier also so I
would mean the first point that is main
concern that we observe in the trend of
for the screaming and the first one that
people observe is that as you move from
after on the atomic number increases
rapidly or we will say very much change
from the mu mu from Abdullah in the same
note similarly we have talked about this
earlier so for example if I'm talking
about lithium lithium as an atomic
number of 3 right talking about the
sodium which is belong to in the same
block or we could say which is down to
the same group that is s block that we
are talking about then what happens is
lithium sodium potassium and going on
further down we could see that the
atomic number goes on increasing rapidly
so now this is what we have ditalion
because of the atomic number increases
rapidly and we could observe that the
electrons that are
engaging this will lead to the number of
shells will not remain the same
throughout men we are talking in terms
of period it will go on increasing so
that for the number of shell or the
number of main shell increases the
number of ninja increases for example if
I am talking about lithium lithium as an
atomic number of 3 so I could write it
as 1 X 2 2 X 2 1 X 2 or 2 s 1 that means
the outermost shell it has it has
basically two fins but when we are
talking about sodium we could write it
as the letter no convolutions sodium as
1s2 2s2 2p6 3s1 so the number of mention
is now 3 and when we are talking about
the protection so it will have an extra
mention so what happens is the number of
shell will go on decreasing so because
the number of shell will go on
increasing that means that the number of
inner electron will also go on
increasing so therefore the number of
inner electron energy electrons
increases and because of this even
electron they go on increasing so what
will happen actually the inner electrons
will try to shield the nucleus first
they they it should not have that
machine fits on the optimal selector and
this is missing mentioning in pattern
shooting if it is basically observed
when we move from up to on or down the
group and that's the reason because of
the energy across that increases when we
move down to the group so therefore this
will result in increase in screaming
effect so therefore
skidding effect increases and that's the
reason what happens is so that's the
reason what happens is the nuclear
charge goes on decreasing so that's what
the nuclear charge it decreases and
since the nuclear charge goes on
decreasing densities and the atomic size
goes on increasing so it is not only a
tiller because there are various factors
that may affect the atomic size so among
that we have also studied that among
that the mention was also the main
reason because as we move from left to
right that is around the period so the
atomic shell that is the number of shell
it it remains constant when we come up
to down that is down to the group so
atomic shell the number of shell it goes
on increasing as well as the number of
electrons also goes on increasing but
when we are concerned with a screening
effect then we would observe that the
inner electrons also goes on increasing
energy electrons also goes on increasing
test results even more sweeping effect
and hence you can see that the nuclear
charge decreases and hence the atomic
size increases so let me give a short
example of this so that you could
understand in very better so for this
example let me talk about a period
suppose the same like sodium if I would
concern that for that thing sodium and
Magnussen's
so in periods what we observe this when
we are talking about sodium and
magnesium sodium has an atomic number of
11 while magnetized atomic number of
good and they both are belonging to the
same P so in this case suppose if I draw
the schematic atomic structure of sodium
so
if it really consists of patients while
the Magnusson it always it will consist
of the same since it is same number of
sheets as insomnia so the thing is the
outermost electron the other most Shen
will come sister of money later when it
comes to sodium while it when it comes
to the magnanimity consists basically
doing drugs and whatever what we could
observe is people to observe that the
inner electrode in this case and
basically and because the second shape
the first share it includes to later on
when the second shall consist of eight
electrons so it consists of a difference
and moreover here also it will be the
same that is eight electrons would be
here and to let us will be the inner
motion
so as we could move as we move from left
to right so the main shell remains the
constant means it might be sodium
magnesium or aluminum and it will
silicon anymore so the number of shell
remains of the main shell remains
constant and because of which what
happens is the inner electrons also
remain the same
and but what we could observe is that
the electrons are entering the outer
shell and because the electrons are
entering the outermost shell so what
will happen the force of attraction
within the nucleus and the outermost
shell it will be more and that system
also so that the atom sex goes on
decreasing because the nuclear charge
goes on increasing and consider there
will be more change in no drastic change
in screaming in fact it was the
electrons belongs to you in the signal
thrown the whole when we are talking
about the period so that's the reason
the screaming effect has not so much of
change and reversibility atomic size
decreases so this was the related to
period so let me talk about when we are
talking about you so when we are talking
about a group for example I will take
the first example X Keesha
first we take lithium and then you
famous a number of three men sodium
which has out of the number of missing
eleven so as we this is the second
collision we it comes sodium so as we
can see that the Arabic number doesn't
change gradually
by a unitary number but it changes
drastically as we would see that the
atomic number is three but now you could
see here it is basically eleven and you
know that you would see 19 so the more
things suppose if I draw a schematic
diagram of this thing so for lithium or
take your draw is this will consist of
basically two electrons in the first
shell and the outermost electron will
contain basically one unit so what when
we are have done the structure or the
dynamic diagram of sodium so I could
write it in this way it will consist of
two electrons in your promotion in the
first shell and after that it is
affecting eight electrons and the autumn
of shell would contains one elector so
this case what we could observe is you
could observe that the outermost
electron consists of one electron proton
would do but the main thing is that the
inner electrons it also changes
drastically because in lithium the inner
electrons are two electrons by when
talking about the sodium which is next
which is just down to the medium it has
total number of ten electrons n
electrons in the innermost or in the
inner electrons inner shells so that's
the reason this inner electrons this ten
inner electrons are competitively more
than that of these two inner electrons
which makes the sodium to have more
screaming effect or more shielding
effect because of which this ten
electrons they will prevent the nucleus
to to have an attraction towards the
outermost electron that's the reason as
we move down to it blue people see that
the screen in fact goes on increasing
and that's the reason the nuclear charge
goes on decreasing and yes the atomic
size goes on increasing so this is what
the tag that I wanted to showcase you so
it also a much simpler to understand so
thank you for watching this video I hope
you have understood this video very
clearly and also what is actually
screaming effect and what are the trends
of it so thank you for watching this
video I hope you will share this we will
end yes
you will not forget to sister be
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