CBSE Class 9 > Class 9 Videos > Dalton Atomic Theory & Thompson Model - Chemistry Structure of Atom, Force & Laws of Motion, Science, Class 9
Dalton Atomic Theory & Thompson Model - Chemistry Structure of Atom, Force
FAQs on Dalton Atomic Theory & Thompson Model - Chemistry Structure of Atom, Force & Laws of Motion, Science, Class 9
| 1. What is Dalton's atomic theory and how does it relate to the structure of an atom? |  |
Ans. Dalton's atomic theory, proposed by John Dalton in the early 19th century, states that atoms are indivisible and indestructible particles that make up all matter. According to this theory, atoms of different elements combine in fixed ratios to form compounds, and chemical reactions involve the rearrangement of atoms. This theory laid the foundation for our understanding of the structure of an atom and the concept of atomic mass.
| 2. How does the Thompson model of the atom differ from Dalton's atomic theory? | |
Ans. The Thompson model, proposed by J.J. Thompson in the late 19th century, introduced the idea that atoms are not indivisible but are composed of smaller subatomic particles called electrons. Thompson's model suggested that electrons were embedded in a positively charged "pudding-like" substance, known as the plum pudding model. This model differed from Dalton's atomic theory by acknowledging the presence of subatomic particles within the atom.
| 3. What is the significance of the force and laws of motion in understanding the structure of an atom? | |
Ans. The force and laws of motion play a crucial role in understanding the structure of an atom. According to Newton's laws of motion, electrons move in specific orbits or energy levels around the nucleus of an atom. The electrostatic force of attraction between the negatively charged electrons and the positively charged nucleus keeps the electrons in their orbits. Understanding the forces acting on the electrons and the motion of these particles helps us comprehend the stability and arrangement of atoms.
| 4. How do Dalton's atomic theory and the Thompson model contribute to modern atomic theory? | |
Ans. Dalton's atomic theory and the Thompson model were significant contributions to modern atomic theory. Dalton's theory laid the foundation for the concept of atoms as the fundamental building blocks of matter and the understanding of chemical reactions. Thompson's model, on the other hand, introduced the idea of subatomic particles and helped refine our understanding of the atom's structure. These theories paved the way for further advancements, such as Rutherford's nuclear model and the Bohr model, leading to our current understanding of the atom.
| 5. What are the key differences between Dalton's atomic theory and the Thompson model in terms of their explanations for the structure of an atom? | |
Ans. The key differences between Dalton's atomic theory and the Thompson model lie in their explanations for the structure of an atom. Dalton's theory proposed that atoms were indivisible and had no subatomic particles, while the Thompson model introduced the concept of electrons as subatomic particles. Dalton's theory focused on the idea of fixed ratios in compound formation, whereas the Thompson model emphasized the existence of a positively charged nucleus and negatively charged electrons within the atom. These contrasting explanations highlight the progression in our understanding of atomic structure over time.
Text Transcript from Video
hello friends this video on structure of
atoms part 2 is brought to you by exam
fear calm
no more fear from exam so let us
understand Dalton atomic theory
Dalton gave various theories and the
first postulate was that all the matter
is made up of very tiny particles and he
called it atoms that is Utne matter
predict apple banana and seal anything
you do that is made up of tiny particles
and that tiny particles called atom
atoms are indivisible particles that
cannot be created nor can be destroyed
in a chemical reaction
this was also postulated by at by Dalton
and this is wrong Eisley we will show
you it is wrong we can actually divide
atom atoms of a given element of
identical in mass and chemical
properties you take atom of any given
element for example you take atom of
sodium or you take atom oxygen or
chlorine atom of sodium will have
identical mass and chemical property all
the atoms of sodium will have identical
mass integral for example you take ten
items of sodium so all these 10 atoms of
sodium will have identical mass and
chemical properties atom of different
elements have different mass and
chemical authority of example you take
one item sodium one atom of oxygen 100
all these three will have different mass
and different chemical properties atom
combined in a ratio of small whole
number to conquer for example water you
see two hydrogen and one oxygen combines
to form water that is in the ratio of
whole number the relative number and the
kind of atoms are constant in a given
compound you take any compound for
example you take water to take water
from various source you take water from
sea lake well tap what the composition
of water will be same the relative
number of hydrogen and oxygen atom will
be constant will always be h2o right
does you have seen that dark Natoma
theory was able to explain the law of
conservation of mass that is you burn a
mistake the mask
the burning in the moss after the
burning will be same or you dne any
matter any chemical reaction the mass of
the reactant will be equal to the mass
of the product law of constant
proportion you take any compound for
example you drink water from any source
the proportion of hydrogen and oxygen in
that will be constant but Darden theory
had limitations for example it failed to
explain the results of many experiments
example glass went up with silk or fir
generate electricity this was observed
but Dalton theory could not explain the
reason for this for example in this case
also if you are up the scale with fur or
silk is generate the charge and you see
the paper dancing so garden theory could
not explain this so you take tall in
that you have this balloon and then this
balloon will tend up a charge when you
try to stick this JA balloon to a wall
it will get stuck so this experiment
could not be explained by Dalton Dalton
could not explain the sub particles that
was discovered later in the 20th century
because Dalton as per Dalton theorem
atom is indivisible
so here various atomic models proposed
we have explained we have told that
function has given a model in 1897 this
is Thompson model then Rutherford gave a
model in 1909 and Bohr give a model in
1902 and then the quantum models will
not show required a model yesterday
these three models so this is the actual
model this is the actual truth these are
all postulate so you can see how this is
all theory because that time the
physicist the physics was not advanced
and we didn't have instruments to
actually view a particular atom because
they are very small in size this we all
guesswork
so let's study the first modular
assumption model C 1898 mr. JJ function
he proposed that the atom poses a
spherical shape of radius 10 to the
power minus 10 meter such a small size
and in which the positive charge is
uniformly distributed and the electrons
are embedded into it in such a manner
that it gives the most stable
electrostatic arrangement that is these
are minded together by electrostatic
force of attraction that was the model
given by function we see in this case we
have only electron and proton there is
no Neutron in this scale because when
the Thompson model was proposed the
neutron was not even discovered my
discovered in 1920 s okay and these some
people call it plum pudding model some
call it raisin pudding model
some call it watermelon model you see is
like plum cake the red part the positive
part is the cake and the electrons here
are icing on the cake see this model
would explain the overall neutrality of
the whole atom because it was the whole
law atom was positive and it had
negative electrons
overall it was neutral but it was not
consistent relate results will see that
it will some experiments will perform
and those experiments were not
consistent with this model okay and as I
told please note Newton was not
discovered at this time so there is no
Neutron in this model so on the basis of
function model explained how atom is
neutral as a whole in this case we see
is a positive charge and similar amount
of negative charge is there but
so overall positive and negative gives a
neutral charge right so if let's suppose
it has five minute of positive charge
then you have five electron so overall
it will be neutral so with this it
explains the neutrality of the thank you
visit our website exam viacom to watch
more and more qualities we should be
news you can also attend free online
tests that are there in our website you
can also get access to tons of free
study materials and you can also find
free tutors and mentors in this website
thanks a lot for watching
atoms part 2 is brought to you by exam
fear calm
no more fear from exam so let us
understand Dalton atomic theory
Dalton gave various theories and the
first postulate was that all the matter
is made up of very tiny particles and he
called it atoms that is Utne matter
predict apple banana and seal anything
you do that is made up of tiny particles
and that tiny particles called atom
atoms are indivisible particles that
cannot be created nor can be destroyed
in a chemical reaction
this was also postulated by at by Dalton
and this is wrong Eisley we will show
you it is wrong we can actually divide
atom atoms of a given element of
identical in mass and chemical
properties you take atom of any given
element for example you take atom of
sodium or you take atom oxygen or
chlorine atom of sodium will have
identical mass and chemical property all
the atoms of sodium will have identical
mass integral for example you take ten
items of sodium so all these 10 atoms of
sodium will have identical mass and
chemical properties atom of different
elements have different mass and
chemical authority of example you take
one item sodium one atom of oxygen 100
all these three will have different mass
and different chemical properties atom
combined in a ratio of small whole
number to conquer for example water you
see two hydrogen and one oxygen combines
to form water that is in the ratio of
whole number the relative number and the
kind of atoms are constant in a given
compound you take any compound for
example you take water to take water
from various source you take water from
sea lake well tap what the composition
of water will be same the relative
number of hydrogen and oxygen atom will
be constant will always be h2o right
does you have seen that dark Natoma
theory was able to explain the law of
conservation of mass that is you burn a
mistake the mask
the burning in the moss after the
burning will be same or you dne any
matter any chemical reaction the mass of
the reactant will be equal to the mass
of the product law of constant
proportion you take any compound for
example you drink water from any source
the proportion of hydrogen and oxygen in
that will be constant but Darden theory
had limitations for example it failed to
explain the results of many experiments
example glass went up with silk or fir
generate electricity this was observed
but Dalton theory could not explain the
reason for this for example in this case
also if you are up the scale with fur or
silk is generate the charge and you see
the paper dancing so garden theory could
not explain this so you take tall in
that you have this balloon and then this
balloon will tend up a charge when you
try to stick this JA balloon to a wall
it will get stuck so this experiment
could not be explained by Dalton Dalton
could not explain the sub particles that
was discovered later in the 20th century
because Dalton as per Dalton theorem
atom is indivisible
so here various atomic models proposed
we have explained we have told that
function has given a model in 1897 this
is Thompson model then Rutherford gave a
model in 1909 and Bohr give a model in
1902 and then the quantum models will
not show required a model yesterday
these three models so this is the actual
model this is the actual truth these are
all postulate so you can see how this is
all theory because that time the
physicist the physics was not advanced
and we didn't have instruments to
actually view a particular atom because
they are very small in size this we all
guesswork
so let's study the first modular
assumption model C 1898 mr. JJ function
he proposed that the atom poses a
spherical shape of radius 10 to the
power minus 10 meter such a small size
and in which the positive charge is
uniformly distributed and the electrons
are embedded into it in such a manner
that it gives the most stable
electrostatic arrangement that is these
are minded together by electrostatic
force of attraction that was the model
given by function we see in this case we
have only electron and proton there is
no Neutron in this scale because when
the Thompson model was proposed the
neutron was not even discovered my
discovered in 1920 s okay and these some
people call it plum pudding model some
call it raisin pudding model
some call it watermelon model you see is
like plum cake the red part the positive
part is the cake and the electrons here
are icing on the cake see this model
would explain the overall neutrality of
the whole atom because it was the whole
law atom was positive and it had
negative electrons
overall it was neutral but it was not
consistent relate results will see that
it will some experiments will perform
and those experiments were not
consistent with this model okay and as I
told please note Newton was not
discovered at this time so there is no
Neutron in this model so on the basis of
function model explained how atom is
neutral as a whole in this case we see
is a positive charge and similar amount
of negative charge is there but
so overall positive and negative gives a
neutral charge right so if let's suppose
it has five minute of positive charge
then you have five electron so overall
it will be neutral so with this it
explains the neutrality of the thank you
visit our website exam viacom to watch
more and more qualities we should be
news you can also attend free online
tests that are there in our website you
can also get access to tons of free
study materials and you can also find
free tutors and mentors in this website
thanks a lot for watching
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Apr 19, 2026 Last updated
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