Rutherford Model - Chemistry Structure of Atom, Force & Laws of Motion, Science, Class 9 Video Lecture

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alpha beta gamma and x-rays what are
these alpha beta particles and gamma and
x-rays see will he Ranjan in 1895
he actually showed that in electron
strikes a dense metric example this is a
dense metal and there's a tone it
strikes a dense material in the cathode
ray tube everything is happening in the
cathode ray tube it produces a ring and
this way actually caused fluorescence in
the fluorescent metal place outside the
cathode ray little sample is a
fluorescent material then this will
create four cells here but he did not
know the nature of this radiation these
radiations you did not know what is the
nature of the radiation and that's why
he called them x-rays normally X is used
blind you don't know what is that right
so that time we didn't know what is the
nature of this radiation and we called
it x-rays and x-ray was thus discovered
in 895 okay and these x-rays were not
deflected by electric and magnetic field
and they have very high penetrating
power and that's why x-ray is used for
finding your bone defect or any other
defect in your body because this
actually has very high penetrating power
okay and suddenly element they emit
tradition on their own and this
phenomena is called review activity
usually important military classes and
these elements are called radioactive
example uranium thorium typically the
element which are at the end of the
periodic table they are review active
elements and they element they limit
radiation on they own these are
typically used for nuclear nuclear power
you have few earlier forms these they're
all these radioactive elements are used
right so they are three kind of phrase
alpha beta particles and gamma this okay
alpha particle a positively charged
particle
beta particles are negatively charged
particles similar to electrons and gamma
particles are highly efficient like
x-rays they are neutral okay and thus if
you see their own they are not deflected
by electric or magnetic field so we have
alpha beta and gamma alpha is positive
beta is negative and gamma is dim please
remember an alpha is positive
helium you are positively charged in a
million beta is negatively charged
particles emitted electron and gamma is
total and gamma are high energy
relations degree example exits okay so
you should remember this alpha is
positive particle is negative particle
and gamma rays done to bring any x-rays
example of ours okay so as regard to the
penetrating power we'll see alpha
particle has a least Finiti power
because if you see it is proton and
proton is heavy in mass 8 since it is
heavy the puritan powerless this is
electron so little heavier than the
proton little lighter than proton so it
has higher penetrating power and gamma
is totally in neutral so gamma rays has
highest
penetrating power
so with this understanding of alpha beta
and gamma particles we will see that one
of these particle is used in the
Rutherford experiment to actually find
out or to give a better or propose a
better structure primer this is all done
on time back when the actual atom
structure was not even known it's on
extreme I come here discussing not so
what he did was he said I did a gold
foil now question is why would foil why
not enemy my not either metal because he
wanted a very thin layer and gold is
malleable
you can have a thousand I don't thik
gold and he can have a very thin or fine
so he do good now alpha particles were
used
why not beta and gamma C as I told beta
particles has a higher penetrating power
gamma has very high anymore so if you
use a very high kinetic power particle
it will pass you the good foil this is
good for if you use alpha particles some
of them will bounce back if you use beta
or gone all of these impossible because
they have higher creating more so they
you so rather for use w w charge helium
ion that is alpha particle so you should
know why alpha material is useful okay
so let's see what is the magic here so
it was expected the alpha particle will
be deflected by the subatomic particles
see if we assume the function model of
atom it's too tall that I'm like this I
did all that like this assuming it's a
Tuan cake you could all the plum-cake
like this and now you're what bombarding
alpha particles what is happened you go
back it will bond back so that was the
expected behavior
a-assuming Thompson model is correct the
expectation was that the alpha particles
all the alpha particle should bounce
back but this did not happen
he saw that most of the alpha particles
went through and only few of the alpha
particles actually got deflected to be
see fewer property has got deflected out
of these many 1 2 3 is deflected in
another arm they are passed through what
does that mean that means that the atoms
are not dense as explained in the
Thompson model that means there is
something or nucleus which has a mass
and it is all air after that because if
that is the case then only if you see
this particle will pass through this
particular one because the alpha
particles alpha particles they don't
have high penetrating power but to his
surprise when you using a thin gold foil
and in that is you see this is a thin
gold foil let suppose
this cold fire will have atoms see there
isn't my veto gold foil if he took some
other foil aluminum IAM so this is will
have so many items like this or one
strip of india fine because you can make
only this much thin nvm but goal didn't
have anything there when you're thin for
a night we can have this kind of screen
and we are looking for a very thin foil
because this is the source of
automatically and this is the coil and
this one has to be attractive because if
it is very thick you won't get correct
data it has to be anything because a
small amount of metal will have millions
and millions of atoms that we have seen
so even if we are really really thin
thin foil so that it will have minimum
number of atoms okay because you see
this is the gold foil we have in this
gold foil also you see these other
adults take this and these atoms also
actually not one there if you actually
see they are three four layers like this
because the atoms are very small in size
I told you 10 to power minus 10 meter is
the diameter so we being really really
thin foil and the most malleable and
ductile metal is wood so we are using
godean the Rutherford use Gordon so but
this experiment he found that this was
the observation this is a set of a tree
so he has put a gold foil here and he is
forced and then he found that most of
the particles went straight and only few
of them got deflected here you see only
few of them were directly
okay so with this he observed that into
most of the fast moving alpha particles
pass straight to the world boil some of
the alpha particles were deflected by
small angles and only few one out of
twenty twelve thousand particles
appeared to leave only one hundred to a
thousand particles rebounded land if you
see very few particles rebounded back
and most of them passed through and few
of them deflected that was no
observation so with this observation he
concluded that this is same scenario
like this example let's assume these is
my atom hey your manners this is the bar
quietly okay and these are my alpha
bodies so you may throw my alpha
particles like this throw pebbles on
this Bob pile you'll see that most of
them will pass because your table or
stone is very small and the gap is more
very most of them will faster and only
few of them will actually be deflected
back same thing is happening here this
is the gold foil it's a gold foil and it
from this gold foil you are parting this
is the one foil this is a good one and
this gold foil
most of them passed that means
the atom is not dense because if you
make this as very dense right you make
big solid walls you put solid walls here
then in that example the same boy
instead of that you have something like
this real solid balls right all the
girls all it was and now if you pass
through pebbles
whatever you'll see most of them will be
different to back but in this case most
of them went true that means you try to
do that in an town most of the space is
empty space and since few of them
actually deflected that means there is
something which is very hard at the
center right so if you see the
conclusion that most of the space inside
the atom is empty because motion by
alpha party has actually passed to the
gold foil without being deflected okay
and very few particles are deflected in
the path is indicate that the positive
charge this postage are the black one
occupies a very little space okay and a
very small fraction of particles were
deflected it indicated that all the
positive positive charged in the mass of
the gold were concentrated in a small
volume this is not hope you understand
the experiment right with this
experiment the Rutherford conclude that
the digit function model was not correct
actually in an atom you have something
called nucleus which has most of the
mass and then we have electrons around
it so with that he came up with this
kind of model he told that this is a
time not and most of the masses here
most of the ones with him is called Li
please
and then electrons are something here
thank you told that the positive charge
most of the mass of the atom are densely
concentrated in the extremely small ISM
and these very small portion of the
êtes-vous corn you place and it is
agri-food who gave this term Lewis
because prior to worker for there was no
concept of nucleus and the size of
nucleus is very small as compared to
size of Adam and we have told you also
in the nucleus is cricket ball then the
size of the atom is Phi equal emitter
radius okay and to maintain the new
trilogy the nucleus is surrounded by
this electrons and these electrons move
in a very high speed in some orbits okay
and then he exclaimed
Rutherford explained this as solar
system this is the Sun you have Sun
symbol here you have all the spot right
yeah
Mercury Venus Earth like that so he he
told nad the atom is almost similar to
the solar system we have right the Sun
is nucleus and the electrons move around
in the orbits circular orbits so the
nucleus is the Sun and the electrons is
the plan that's how he compared
okay that was the other foot model and
he told that these electrons and the
nucleus are held together by
electrostatic force of attraction
because the nucleus is positively
charged electrons are negatively charged
so they held together by electrostatic
force but rising but it had some
limitation the limitation was C the
orbital revolution of the electrons
which he proposed is not expected to be
stable because in physics we have seen
that any particle in a circular orbit
will actually enter go accidentally so
when it is accelerated these charged
particles will radiate some energy these
electrons will radiate some energy if
the energy is related these particles
will lose energy and once it lose energy
it should finally come back in for into
nucleus because it is negatively charged
this positively charged positively
charged nucleus will actually a tribe is
negatively charged electron and this
electron should fall back into the
videos
right if that is the case the electron
becomes highly unstable so what is that
force which is keeping these electrons
apart there are so many doubts in this
model all the questions were not
answered the stability of the atom was
not explained could not be explained
properly with our other fourth at a
model right and with that we will see
that Bohr also gave a model before that
let's see one question on the basis of
Rutherford's model which subatomic
particle is present in the nucleus of an
atom see whether for gain is moral that
time only electron and proton was
discovered one discovered so a spur to
the foot model electron is present in
the orbit and in the nucleus we have
only photon it's all this is another
model proton is the only particle is the
nucleus so then we please be Emil what
do you think would be observational the
alpha particle scattering is carrying or
using a foil of metal isn't in the hood
see you take any other metal let's take
a metal copper copper if you take a
small piece of copper the cross-section
will be something like this one because
the copper is not much malleable and you
can't make a very thin film of over so
even a small piece of copper will be
something like this so many items
provider for multi
it is the thickness of the copper you
take it suppose this is a copper you
take this mistake and if you take this
must in accord since it will be a little
thicker and it is good
this is gold it emits blue cross section
so you see here the number of atoms less
the given cross section is good it is
cooperative so this is the thing falling
and this is 10 we are going to thin foil
because if it is very thick while most
of the alpha particles then walk back
and you'll not be able to conclude so in
that case you will assume that the
Thompson model is correct it is thin
foil you can actually include that
function model is incorrect Annika
actually give a proper better model 1 I
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