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advanced videos Hello Friends in the last
lecture we have shown you about what is
atomic radius and what are the factors
that will be a topic that will affect
the atomic duties and now what we are
going to do is we are going to do that
what are the variations of atomic radius
that we are going to see imputable and
what are those let us see
so welcome to variation or when we say
that what is the periodic pender when it
comes to the atomic radius then it is
being observed just for the period and
the groups so let us talk about what
will happen when we are talking about a
period or what are the variation that we
would see for an atomic size map we are
talking about elements that we are
following in an bin so so impedance what
we observe is as we move from left to
right as we move from left to right in
the periodic table so what happens is
the atomic number increases gradually so
what we could see is that is atomic
number increases gradually and because
of which the atomic size also increases
or moreover if we could say if the
atomic number increases then what
happens is the number of electrons will
also increase gradually another thing is
the electrons now that are being
increasing and that electrons are being
added in the same shape talking about
this thing suppose when we are talking
about the sodium so what happens is if
the atomic number increases that is from
sodium which has an atomic number of 11
and then we move to magnesium so
therefore what happens is magnesium has
an atomic number of two it so this
electrons this extra electron that we
add up in the third shell only so what
happens is the number of electrons that
are being added in the same shell so
that happens that is what it makes us to
understand that the nuclear charge will
increase so what happens is the nuclear
charge increases
so the nuclear charge increases because
the electrons are added up in the same
shape and because the electrons in the
outermost shell are being normally move
because they are increasing and as you
move from left to right so if they are
increasing then what will happen the
nuclear charge will increase they will
have more attraction toward as a central
nucleus that consists of protons so that
kind of nuclear charge will be more in
case of when we move from left to right
so this makes the atom to have the
atomic size in less so that is the
reason as we if we move from left to
right the atomic size decreases so
therefore the atomic size decreases in
period as before as you move from left
to right so this was the first variation
that we have observed in when we are
talking about a period so now let us
talk about what will happen in groups
swing group so group is the one that we
have that we know that is the it is a
very it is a vertical column and you see
the atoms are being are the elements are
being arranged in such a manner that
they have a similar properties so
talking about the first group that is a
group one which consists of a lithium
sodium potassium and all so then in that
case what we observe is the atomic
number increases the atomic number
increases but not gradually they
increase rapidly for example if you if
you are talking about lithium lithium
has an atomic number of 3 but that of
the sodium which is belonging to the
same group has an atomic number of 11
and when we are talking about the
protection mirgain which is belonging to
the same group that is group 1 in the
protectable it has an atomic number of
19 so the atomic number increases not
gradually decreases rapidly or as you
could say that we could say large
difference when we are jumping from the
upper element to the lower element so
therefore this is the atomic size that
we
please that we see that it increases
rapidly so what does this affects and
how does it this affects the atomic size
because as the atomic number increases
rapidly and we could observe that the
number of shell also increases so what
will happen in periods it was the number
of shells which was almost the same but
even when we are talking about the
atomic Arabic number or atomic size of
many we are talking in group and atomic
size increases because the number of
shell increases as you move down the
room so if the number of shell increases
obviously the number of electrons will
also increase that will result in the
atomic size to be larger then come and
there will be no gradual increase there
will be rapid change so because of which
what happens is the nuclear charge the
effective nuclear charge will be less
because as in impersonally increases the
nuclear charge will be less so therefore
the nuclear charge is less so because of
which what happens is if the effective
nuclear charge decreases then the atomic
size will increase so that is the reason
the atomic size increases so these are
the main reasons that when we are
talking about the periodic trend about
the property like atomic size in period
so the atomic size decreases because the
nuclear charge also increases and
moreover the electrons are being added
in the same shell or the same valence
shape and because of which the atomic
size decreases and when you are talking
about a group then what happens is the
electrons increases rapidly and moreover
the number of shells increases and
because of which the atomic size also
increases and in this results in the
atomic this results in the nuclear
charge to get reduced was the effective
nuclear charge that decreases because
the creature is nothing but the
attraction of the nucleus with the
outermost electron so
this increases that if this nipple
charge decreases then obviously the
atomic size will go on increasing so
these are the two tents that we have got
to see when we are talking about the
property known as atomic size for
periods as well as for groups so thank
you friends for watching this video I
hope you have liked this good idea what
does should this ones are very clearly
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