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advanced videos Hello Friends  in the last
lecture we have studied about what is
Valence as well as we have also got to
know that how the valancy changes
that is we have also destroyed that what
are the types of trends in periodic table
so now we are going to study about what
is oxidation state and what are the
variations that we could see in the
periodic table so let us take it up
so now we are going to do the study of
what is actually oxidation state so what
is the oxidation state actually
oxidation state of an element in a
particular compound can be defined as
the charge acquired by its atom on the
basis of electronegativity of the other
atom in the molecule through which it
has been attached for example what does
it says suppose we know that whenever we
are talking about a covalent bond or a
molecule for example in this case I will
consider the example of again I can take
the example of Excel also but suppose
let me take the example of KCl so this
case it is a molecule that is composed
of potassium as well as the chlorine
atom as we do so this molecule basically
consists of the potassium which has
basically partially positive charge upon
that of the chlorine atom which has
partially negative charge so this
partial negative charge that makes the
oxidation of the chlorine to be as we
can also state that the oxidation state
of the chlorine atom and this molecule
will be
- one so if the oxidation state of the
chlorine is minus 1 then the oxidation
state of the potassium will be plus 1
because it means will be the charge
acquired by the atom when the other
molecule is also attached to it and
based on the charge at a tech voice for
the potassium it will depend on the atom
which is Bennett actual so in this case
the potassium is an atom which is being
attached or which is being bonded with
the chlorine atom as well as we know
that the chlorine is more
electronegative so what will happen that
the chlorine will pull the electron
towards itself whenever we are talking
about a covalent one so what will happen
is drawing will now be more
electronegative then compared to that of
the protection so that makes the
potential to have a positive charge so
therefore this positive charge that we
compare with a positive charge item and
a partially negative charge atom will
make a rise in oxidation state and hence
the potassium will have the oxidation
state of +1
so this is how we could depreciate that
what is oxidation state it is any easy
to understand but this was a molecule
which consists of two atoms but there
will be also a few items that we know
that consists of more than two atoms
basically three atoms or four atoms so
let us talk about that also
but for that instance let me give an
example and let us see that what will be
the oxidation state of this atoms that
have been present in the molecule for
example if you are talking about this
molecule that is oxygen fluorine so in
this case basically the oxygen is been
only 1/10 so while that of the fluorine
is being repeated two times so in this
case or the bond can be written as as we
know that the valency of the oxygen is 2
so that means we could write this one
clear formula that is or basically could
say it is the molecule that has been
present in front of us so we could write
this thing s in this manner also it's
very easier to represent in a structural
formula so as you can see that the
flowing has been attached to oxygen and
again this oxygen is will attach to the
fluorine and moreover we know that
oxygen is electronegative as well as the
fluorine is also electronegative atom so
instead of having this two are
electronegative but how can we say that
what would be the oxidation state of a
particular atom like fluorine in this
case so for that instance we know that
flowing is the most electronegative atom
of the whole periodic table when it
comes to an T element so therefore it
makes the fluid to have between
partially negative charge so in this
case the fluorine atom will have
partially negative charge so this will
make us to understand that the fluorine
atom will acquire or will try to pull
the electrons of oxygen also towards
itself so this electron of
the oxygen will be pulled towards the
fluorine as well as this electron of the
oxygen because a bond is made up of two
electrons at least so in this case as we
know that in this case what happens is
electron is been pulled by this fluorine
so this pooling of electrons of the
fluorine because the fluorine is the
most electronegative atom or we could
say the predictable so that will make an
influence that the oxygen being the
electronegative also but it is less
electronegative than that of fluorine so
now in this case this will acquire
partially positive charge so in that
manner we could say that the oxidation
number of fluorine is always minus one
so therefore in this case the oxidation
state of fluorine is minus one but in
this case of seeing that as you know the
oxygen has a valency offered two and
when it comes to the charge it acquires
-2 charge but in this case with signe in
this example since oxygen is behaving as
if a partially positive charge so in
this case because it is also been
attached to two fluorines so therefore
in this case the oxidation number or the
oxidation state of the oxygen will be
said to be +2 so therefore the oxidation
state of oxygen is +2 so this oxygen is
now plus 2 while each fluorine atom that
have been present in this molecule is
minus 1 so basically this will overall
make the species or make the molecule to
be electrically neutral because the
oxidation number will cancel out each
other but when you are talking about the
individual that is when you are talking
about the oxidation state and as we know
the oxidation state will depend on the
electronegativity of the other sources
now in this case because oxygen was said
to be we say an electronegative atom but
because it has been attached to flowing
which is more electronegative now it has
acquired a partially positive charge
which makes the oxidation state of the
oxygen to be
plus two in this case but in case of h2
we know that the hydrogen is more to
positive while that of the oxidized mole
a tourniquet so in that case that is an
h2 that we know that most of the models
that we know in which the oxygen equals
minus 2 charge or partially negative
charge when it has become vanadium in a
combined state to 4 molecule so
therefore oxygen h2 will have minus 2 as
the oxidation state when the hydrogen we
have plus 1 as the oxidation state but
in this case it is quite different so
that's the reason that we should
understand that what is oxidation state
so therefore we have understood that
constant also so now let us learn an
another process in which it would be
very much easy to understand for example
in this case that is an 8 - oh that is
disodium oxygen or it could say sodium
oxide so in this case basically what we
could say that in any - oh that is die
sodium oxide in which we could write the
structural formula like this one
so this sodium oxide basically and in
this case it can dis consists of four
two sodiums and one oxygen and moreover
we know that oxygen is the one which
belongs to the P block and basically we
know that it is electronegative compared
to that of the sodium and sodium is
belonging to s ro and as blocks are the
and asthma consists of the elements
which are basically like to positive or
which has the tendency to lose electron
so that in the case if sodium is losing
electrons so therefore it will acquire
positive charge partially positive
charge in this case so mean like that
electron will be pushed towards the
oxygen in this case and oxygen will be
more electronegative because it is
actually electronegative but now it
because of the sodium it will be more
electro negative so now what will happen
so the oxidation state of sodium in this
case because it is been repelling
etcetera or it is being donating its
electron mostly towards the oxygen when
it is combined in a similar form
so therefore the oxidation number or the
oxidation state if I would say more
precisely that the oxidation state so
now therefore for sodium we could say
that the oxidation state of sodium is +1
so for both the sodium's means for each
hole in the oxidation state would be +1
so as to compensate this thing a
negative charge is been required or
moreover we could say that because of
oxygen which is more electronegative
then compared to that of the sodium so
now when we are talking about the
oxygens oxidation state so therefore the
oxidation state of oxygen is minus 2 so
this will be having an oxidation state
of minus 2 as sodium will have oxidation
state of plus 1 so now in this case they
are now being compensating each other
when it comes to the charge or oxidation
state so in this case basically the
whole molecule is now in Newton and we
could say that this is what
the melon sees also been showcased in
this case because because as we know
that the oxidation state of the oxen is
minus 2 that means it can form two parts
with a univariant item so that's in this
case basically oxen is been attached to
two univariant items mainly sodium in
the previous example also that we have
took me have took the example of firm
that is f 2 O and in that case what we
have got now again oxen is a one which
is forming two bonds with univariant
term atoms like fluorine
so therefore that is in that case also
we have got another in the valency of
the oxygen is two but and also in case
of the flowing we have got to know that
tie it it's wet and C is 1 so this is
how we could understand oxidation state
a very easy concept and talking about
the oxidation state this oxidation state
of the oxygen sodium and fluorine they
are being fixed or or it depends it to
which it has been attached but there are
a certain elements in the periodic table
which don't have a specific oxidation
state for example if you are talking
about d-block elements or we see they
are known as functional metals or
transition elements this elements have
the tendency to lose electrons they get
lose one electron they can lose two
electrons means depending on the electro
positivity or oxidation state their
oxidation number changes or oxidation
state changes for example Fe that is
iron iron when forms in a Fe 2 plus
oxidation state of I am suppose it is
plus 2 then that is known as ferrous
I think the oxidation number of the iron
it is supposed plus C then it is known
as fighting so basically the oxidation
state of the ion also changes when that
of when we and depending on that to
which item it is been attached to and
depending on that all the d-block
elements has a capacity to show
different oxidation state most of all
and talking about the block elements a
block elements base is known as
lanthanides and the actinides even they
have the tendency
variable oxidation state so when we move
from lanthanum to the last element of
the f-block so he could see that the
observation number varies and while that
of me could similarly we could see me
change or the trend it would be observed
for acting at also because the oxidation
state of the metals also change this
depending on with whom it is bayonetta
with which atom it is being attached to
by talking about the oxidation state of
the s-block
condition while talking about the
oxidation state of the s-block
like the first group and the second
group the oxidation state of the first
group that is when it starts from the
lithium to francium so the oxidation
state of those Eggman's stays plus what
will you buy that of the group ii
elements like from beryllium so it the
whole group elements have the oxidation
state of plus two so this is the
variation that people see and many comes
to the this is what we have talked about
the group and when we go to the across
the period then even that also we could
see that there would be variations in
oxidation number because as we have
talked about lithium sodium has an
oxidation number of plus one but but
while that of the beryllium it is plus
two and you can go on just like the
valency that we have did in our previous
section so it is very simple to
understand that what is oxidation state
and moreover in this case we have got to
know that in depends on thee that is
electronegativity of other component
while emergency is the one that we have
study isn't it depends on the number of
electrons that are present in our motion
and because of Pichet the also changes
when we go across the group or when we
see the variations in the periodic table
across the room so this is was a very
simple company that I have shared with
you so thank you for watching this video
I hope you have liked this video and you
have understood the concept of oxidation
state and you share this with your
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