Isotopes and isobars Video Lecture - Class 9

hello friends this PD on structure of
atoms part eight is brought to you by
example calm no more fear from exam
let's understand a new topic or isotopes
display at agent here C in danger in the
real world it is seen that the number of
atoms of some elements have been
identified they have seen my atomic
number but definite ohmic mass same
number different atomic mass if you see
as I told Adamic our number is the
critical point so the atomic number is
different that means you are talking
about two different elements for example
hydrogen atomic number one and to make
pass to I have twisted number one atomic
mass to hydrogen atomic number one item
mass 2 this is called plutonium this is
called deuterium this is called tri tiem
these three have seen atomic number
right but they have different atomic
mass
and the example can be carbon carbon
atomic number six atomic mass 12 atomic
mass 14 or chlorine atomic number 17
always atomic mass can be 35 or atomic
mass can be 37 and please note that for
example you take some hydrogen in them
in the jar
it will have some concentration of but
the first one time to this prytaneum
some concentration of second one
deuterium and some constitution of third
one forgiveness right so it may be 30
percent forty percent ten percent it can
be any percentage but it will have
typically the one which is found in
nature with simply carbon also you know
take some carbon from the nature it will
have some percentage of carbon-12 and
some percentage of carbon-14 that is
something which is there in religion now
the question is obviously that li that
part does understand is I sort of I shot
over something which has same atomic
number but different atomic mass right
example we have told you hydrogen three
isotopes covered twice or tops chlorine
two isotopes please remember this is a
very critical term in chemistry I saw
dopes
same atomic number definite among us we
have told that also in a given sample
visible a given sample of carbon will
have different percentage of different
exitos okay and this is the national
nature national phenomena and to
understand this national phenomena
itself this term isotope is defined so
ISO tone as the definition is nothing
but isotope is defined as the atom of
same element having same atomic number
but definite ohmic mass okay and
actually most of the element you see it
consists of the mixture of isotopes they
told you so if we take carbon hydrogen
in the jar it will have all the isotopes
in different quantity be it on the
rocker and for example carbon 12 is
almost 99.9 percent and carbon 14 is
almost point by person we talk about
chlorine chlorine 70 35 is almost 75
percent and chlorine 37 is almost 25
percent so if you take chlorine from men
from the nature it will have both these
chlorination with 75 percent log
chlorine 35 and 25 percent of chlorine
37 and thus if you see it would take you
in from nature what will be the mass
will the mass be 35 will the market 37
then we take a verage
then and that's when you must have seen
the chlorine atomic mass is 935 not 37
it is generally thirty five point five
right but atomic mass be as I told you
is nothing but number of protons and
neutrons the number of protons and
neutrons cannot be thirty five point
five it has to be a national number so
that is the average atomic mass of
chlorine please know the atomic mass of
chlorine is twenty five or thirty seven
so if you take a sample combination it
will have twenty four thirty five
percent of the chlorine which is having
atomic stamp mass 35 and 25 percent of
chlorine will have a coming master visa
so we talked about sample atomic mass
the average atomic mass then you do is
you define the average comes out to be
twenty five point five will use the mass
on that okay see if the element has no
isotope example gold then the mass of
the atom will be nothing but the sum of
protons and neutrons the simple formula
which we have seen but if the element
has isotopic form then we have to know
the percentage of each of these isotopes
and then we have to find the average
mass okay example we can find average
mass of chlorine so protein is a seventy
five percent is 25% if you want to find
the average atomic mass so average will
be this is thirty-five into seventy five
percent
plus 37 to 20 papers so we saw on this
you good 35.58 and that is the average
atomic mass of chlorine please see once
again chlorine atomic mass is fractional
atomic mass but actually you cannot have
and we have told a designation of atomic
masses on the number of protons and
number of neutrons number of protons and
number of neutrons cannot be a
fractional number but this is an average
atomic mass of wood okay and also most
of these isotopes have same chemical
property same chemical probably correct
where we get the atomic number is same
atomic number is same that means the
element the same so they'll have almost
same chemical talked about the
application of these as it offs so then
you see that uranium isotopes is used in
the nuclear fuel then kobold isotope is
used to treat cancer and iodine isotope
is used to treat Boyka and carbon
isotope is used for carbon dating
process to find the age of old vessels
old trees and stuff like that let's
understand a new concept called isobars
in isobars it is atomic mass the same
atomic number is different it is just
reverse of isotopes so it has same
atomic mass but different
and a minimun since the atomic number is
different that means the element has to
be different for example you talked
about calcium 20 is they're coming
number 40 is they're coming mass would
argon 18 is a comic number 40 is atomic
bonds in this case they're talking one
is different but please note since the
atomic number is different both the
elements are to try right so atomic mass
is same or I can say that the total
number of nucleons are same same atomic
mass or seen nucleons count not that
critical concept isotope is more
critical concept because in that case we
have same atomic number same element but
different atomic mass and same
properties but the Phenom ik mass in
this case actually we talked about two
different elements with the same atomic
number but so it definitely number but
same atomic mass and obviously both of
these will have different properties why
because they are two different elements
or villain for the symbol H dnt tabulate
three subatomic particles in each of
them CH is what hydrogen I don't know
alright rhodium is B is what deuterium
and E's treasure so in all these if you
see atomic number is all same in all
these three atomic number is same
because they all isotopes of hydrogen
but mass is different in hydronium
atomic masses to do Tolima diagnosis
three criteria may diminish history
there are three all three isotopes of
hydrogen 1 1 1 2 1 3 in this case we
have to tabulate retried ceramic
particles of atomic particles I have
hold on electron and you know hey these
are the three subatomic particles so
atomic mass is nothing but number of
protons so protons will be one alarm
because the atomic mass is one okay
now the number of proton will be equal
to the number of electron because it is
neutral so number of food will be equal
to number of electron now on the neutron
atomic mass is proton plus Neutron right
this is one is going to do 1 plus 0 2 is
equal to 1 plus 1 3 is you can do 1 plus
2 because these two photon plus Neutron
if you add you get atomic mass so 1 plus
2 is 3
1 plus 1 is 2 1 plus 0 is 1 ok so this
is a tabular form of the three subatomic
particles in each of hydronium deuterium
and right here like the electronic
configuration of any one pair of
isotopes in one pair of ice bar so I
should talk the famous pair I think is
the chlorine which is this is one
chlorine is 35 atomic mass and then
there is 37 and early Mars 75% 25% leave
the result in choir so electronic
configuration depends on number of
electrons right so electronic configures
configuration of electrons electrons the
same in both the case at a 17 atomic so
the electronic configuration ravu the
case will be 287 70 by 287 k l m k k- x
8 at the max sorry k can accommodate at
the max - L can accommodate in the next
8 and this can
eighty so first we'll go here second a -
okay remaining seven we'll come here -
87 is the electronic configuration this
is isotopes let us take isobar isobar a
good example
I just took was calcium and argon both
have same occurring mass that is 40 but
the atomic number is different since the
atomic number is different the
electronic configuration between
difference over calcium it is 20 it will
be two eight can it be 10 see 21st -
comes here's again - comes inhale and
then remaining 10
can I put 10 here know the maximum
number in the ocean will be 8 so it will
be 2 8 8 - 4 Argan first who comes here
next 8 comes here remaining is 8 plus 10
we have already used so he comes here
that is the electronic contribution
please pay attention here this is
correct
- 8 10 this is incorrect
hey because although M orbital cannot
accommodate eating electrons but since
in this case M will be the last orbital
and the last orbital can accumulate at
the minus 8 so at the Mexican to eat
here to require this is the correct
electronic configuration thank you visit
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