Dobereiner's Triads and Newlands Octaves Video Lecture - JEE

hello friends this video in
classification of elements part 3 is
what you buy exam clear calm no more
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video please make sure that you have
watched part 1 and part 2 let's study
ee8 triads so in 1817 the German chemist
joven here you try to arrange this
elements based on similar chemical
properties in two groups and he created
three such clothes and each groups have
three elements and he used to call these
groups us trying so he showed that when
three elements in it in a tribe are it
in the order of increasing atomic masses
the atomic mass the middle element was
almost the average of that make must
know other tool that's what he do
example this is one trial where he has
lithium sodium and potassium he has put
all these three in one time because all
these three had similar chemical
properties then he had put this alkaline
earth metal calcium barium all this
thing in one tribe because it had
similar property he also put the savage
in metals telogen elements actually
chlorine bromine hiding all these in one
try it so if you see in this case if you
find that a McMath of this and this you
IDs 239 plus seven is almost 46 divided
by 2 root III you take these also 137
plus 40 divided by 2 you will get almost
similar to very 7.6 right similarly one
point is 6 point 9 plus 35 point 5
divided by 2 will get seventeen point
nine almost but that's what he had shown
a relation of atomic mass with you can
see properties here you see these guys
all our pocket there are three pockets
e-beam and and they all based on the
chemical profit
but he also showed that in this bucket
you take the first and last coming mass
you add them / - you didn't really know
that's what the relation between you can
say that atomic mass and a property
property of the element right
this was stablished there was a burst
Alice first time in 1817 this guy
established a relation in atomic mass on
the right but they were limitations to
this Dornier tribes he could ante by
only three such tried and that time
please note 33 elements were known but
still they would find he would fit only
you can say mind elements in his trance
and anything the mind elements he
threatened to try it was not for all
only for some but still he showed some
relation between the atomic mass and the
property and that's why we starting this
then this guy came new land and he gave
a new land laws of acting what did was
he arranged this elements based on the
atomic mass he was not bothered about
the chemical property was not even
bothered about the chemical property
right he just arranged based on the
atomic mass for example hydrogen lithium
beryllium boron carbon all the arranged
in the increasing order of atomic mass
you observe that and he started with the
hydrogen and ended with the thorium I
think that was of emphasis element that
time you observe that every eat elephant
is similar to the first example hydrogen
fluorine fluorine it was his observation
they have certain property lithium
sodium potassium has a beautiful body
- him calcium we have seen property
that's what he observed right that was
he observed that they had similar
property so this can see that he found a
new thing called periodicity again say
that right because till now we have seen
that domine and he just found relation
to the atomic mass in the property this
guy found a periodicity of property of
the element right
and these law he called as Newton's law
object because after every eight it
repeats and his almost submit to the
tune we have sorry gamma bother you so
late sorry gamma pathani Ginza so
similar to the tune we have the robbed
in the picking the music and if you see
when a shipment of this verse the diseqc
lithium and sodium right the property is
same it's merely barely a man I even
seeum properties same writer he did all
this thing right he he arranges all the
elements in the order of increasing
atomic mass and then he found that they
follow this periodicity but it had
limitations for example this a bucket in
one is also bucket and once they are
some limitation which is starting the
next slides so the limitation of this
new lon
you lands law octave is like this guy is
applicable only to calcium after calcium
whatever the new elements found they did
not fit in his cuban
only it will catch and this was fine
after calcium the the repetition of
property was not perfect does not profit
and it was assumed that only 56 element
existed
so please note he assumed my only hip is
excelling in this issue because at that
time only two six elements there but
later on new new elements came rate
chemist discover thought of new element
so and the new elements never caught a
space in his table also he adjusts it
two elements in one group example cobalt
and nickel
this gives part of one right one group
so this is something which you should
not write you're ordering you're putting
it in the group you should have only one
lemon right so you're putting this guy
put two elements together in a group so
that was something was questionable by
our people and then also if you see this
iron iron
resembles property of cavada nickel if
you see right but they are so far
correct also if you see cobalt and
nickel and chlorine they don't have any
contraband T by chlorine flowing roba
they are different Ashley covert a
nickel on metal and chlorine or material
there are totally different things but
if you see they are put together so the
placement was not perfect it had issues
and the issues where you see the iron
and the copper and nickel they are very
far but they have similar Robert II see
chlorine and cobalt and nickel they ware
of together but they don't have common
property right and also commodity
because he has he has together that is
also questionable so it had not of
limitation but again it short or one
thing that is periodic periodicity of
elements properties does exist may be
the way he found was incorrect but there
is something that can be explode right
and then we had a new guy that came but
before that let's go for some questions
the first question is did the oven air
train also exist in Newlands law act so
let's see this this is my java near
trains the new one and my new alarms law
vector the green one
let's see lithium sodium potassium is it
there yes lithium sodium potassium is
there that means this guy exists right
cas RBA is there calcium as RBA is not
there so this guy does not exist
CL bri chlorine bromine iodine fluorine
is there drawing is there ID is not here
right so that means this guy also does
not exist so we see only one tribe or
only one dog near try it is part of new
lon new lands love it right so only one
dog near try it is part of he wants it
so the question says what are the
limitations of domine
as we know that that time the way 33
elements known but not all the elements
could be classified in on the DA veneers
tried only three tried with three
element East against against it at nine
elements where far of his classification
other elements were not part of this
classification there was the limitation
of the dominant classification the next
question says what are the limitations
of Newton's law octave so they're on
lamination the first thing as I told was
fully up to calcium we can accommodate
right that follows the porosity after
that they are issues with that till
calcium things say fine but after this
it was not following the pattern
actually and the second thing was the
new elements which gave right the new
limits we should discover after that
they were not I come on in that was one
issue right and this guide you see right
cobalt and nickel they were together
that was wrong right and if you see the
iron is far away from this guy quarter
nickel is again wrong and chlorine and
cobalt and nickel are in the same group
that's again wrong because they don't
share them same forward the limitation
of the un's law ABC are the elements of
the oven you tried atomic mass of is 7 D
is we do not know and C is 39 you
defined a comic Mesabi so this guy
ordered atomic mass of B has to be the
mean of these two so that will become 7
plus 39 divided by 2 and then he come
out to be 23 and that's nice easy so
this guy don't write so you have this 3
element in the central property and you
create you tried out of that so the
atomic was a first and then I mean last
you take the mean having mass off thank
you
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