NCERT Textbook: Matter in Our Surroundings Notes | Study Science Class 9 - Class 9

 Page 1


As we look at our surroundings, we see a large
variety of things with different shapes, sizes
and textures. Everything in this universe is
made up of material which scientists have
named “matter”. The air we breathe, the food
we eat, stones, clouds, stars, plants and
animals, even a small drop of water or a
particle of sand – every thing is matter. We
can also see as we look around that all the
things mentioned above occupy space and
have mass. In other words, they have both
mass* and volume**.
Since early times, human beings have
been trying to understand their surroundings.
Early Indian philosophers classified matter in
the form of five basic elements – the
“Panch Tatva”– air, earth, fire, sky and water.
According to them everything, living or non-
living, was made up of these five basic
elements. Ancient Greek philosophers had
arrived at a similar classification of matter.
Modern day scientists have evolved two
types of classification of matter based on their
physical properties and chemical nature.
In this chapter we shall learn about
matter based on its physical properties.
Chemical aspects of matter will be taken up
in subsequent chapters.
1.1  Physical Nature of Matter
1.1.1 MATTER IS MADE UP OF PARTICLES
For a long time, two schools of thought prevailed
regarding the nature of matter. One school
believed matter to be continuous like a block
of wood, whereas, the other thought that matter
was made up of particles like sand. Let us
perform an activity to decide about the nature
of matter – is it continuous or particulate?
Activity ______________1.1
• Take a 100 mL beaker.
• Fill half the beaker with water and
mark the level of water.
• Dissolve some salt/ sugar with the help
of a glass rod.
• Observe any change in water level.
• What do you think has happened to
the salt?
• Where does it disappear?
• Does the level of water change?
In order to answer these questions we
need to use the idea that matter is made up
of particles. What was there in the spoon,  salt
or sugar, has now spread throughout  water.
This is  illustrated in Fig. 1.1.
1.1.2 HOW SMALL ARE THESE PARTICLES
OF MATTER?
Activity ______________1.2
• Take 2-3 crystals of potassium
permanganate and dissolve them in
100 mL of water.
Fig. 1.1: When we dissolve salt in water, the particles
of salt get into the spaces between particles
of water.
* The SI unit of mass is kilogram (kg).
** The SI unit of volume is cubic metre (m
3
). The common unit of measuring volume is
litre (L) such that 1L = 1 dm
3
, 1L = 1000 mL, 1 mL = 1 cm
3
.
1
M M M M MATTER ATTER ATTER ATTER ATTER     IN IN IN IN IN O O O O OUR UR UR UR UR S S S S SURROUNDINGS URROUNDINGS URROUNDINGS URROUNDINGS URROUNDINGS
Chapter
2020-21
Page 2


As we look at our surroundings, we see a large
variety of things with different shapes, sizes
and textures. Everything in this universe is
made up of material which scientists have
named “matter”. The air we breathe, the food
we eat, stones, clouds, stars, plants and
animals, even a small drop of water or a
particle of sand – every thing is matter. We
can also see as we look around that all the
things mentioned above occupy space and
have mass. In other words, they have both
mass* and volume**.
Since early times, human beings have
been trying to understand their surroundings.
Early Indian philosophers classified matter in
the form of five basic elements – the
“Panch Tatva”– air, earth, fire, sky and water.
According to them everything, living or non-
living, was made up of these five basic
elements. Ancient Greek philosophers had
arrived at a similar classification of matter.
Modern day scientists have evolved two
types of classification of matter based on their
physical properties and chemical nature.
In this chapter we shall learn about
matter based on its physical properties.
Chemical aspects of matter will be taken up
in subsequent chapters.
1.1  Physical Nature of Matter
1.1.1 MATTER IS MADE UP OF PARTICLES
For a long time, two schools of thought prevailed
regarding the nature of matter. One school
believed matter to be continuous like a block
of wood, whereas, the other thought that matter
was made up of particles like sand. Let us
perform an activity to decide about the nature
of matter – is it continuous or particulate?
Activity ______________1.1
• Take a 100 mL beaker.
• Fill half the beaker with water and
mark the level of water.
• Dissolve some salt/ sugar with the help
of a glass rod.
• Observe any change in water level.
• What do you think has happened to
the salt?
• Where does it disappear?
• Does the level of water change?
In order to answer these questions we
need to use the idea that matter is made up
of particles. What was there in the spoon,  salt
or sugar, has now spread throughout  water.
This is  illustrated in Fig. 1.1.
1.1.2 HOW SMALL ARE THESE PARTICLES
OF MATTER?
Activity ______________1.2
• Take 2-3 crystals of potassium
permanganate and dissolve them in
100 mL of water.
Fig. 1.1: When we dissolve salt in water, the particles
of salt get into the spaces between particles
of water.
* The SI unit of mass is kilogram (kg).
** The SI unit of volume is cubic metre (m
3
). The common unit of measuring volume is
litre (L) such that 1L = 1 dm
3
, 1L = 1000 mL, 1 mL = 1 cm
3
.
1
M M M M MATTER ATTER ATTER ATTER ATTER     IN IN IN IN IN O O O O OUR UR UR UR UR S S S S SURROUNDINGS URROUNDINGS URROUNDINGS URROUNDINGS URROUNDINGS
Chapter
2020-21
SCIENCE 2
• Take out approximately 10 mL of this
solution and put it into 90 mL of clear
water.
• Take out 10 mL of this solution and
put it into another 90 mL of clear water.
• Keep diluting the solution like this 5 to
8 times.
• Is the water still coloured ?
1.2.2 PARTICLES OF MATTER ARE
CONTINUOUSLY MOVING
Activity ______________ 1.3
• Put an unlit incense stick in a corner
of your class. How close do you have to
go near it so as to get its smell?
• Now light the incense stick. What
happens? Do you get the smell sitting
at a distance?
• Record your observations.
Activity ______________ 1.4
• Take two glasses/beakers filled with
water.
• Put a drop of blue or red ink slowly
and carefully along the sides of the first
beaker and honey in the same way in
the second beaker.
• Leave them undisturbed in your house
or in a corner of the class.
• Record your observations.
• What do you observe immediately after
adding the ink drop?
• What do you observe immediately after
adding a drop of honey?
• How many hours or days does it take
for the colour of ink to spread evenly
throughout the water?
Activity ______________ 1.5
• Drop a crystal of copper sulphate or
potassium permanganate into a glass
of hot water and another containing
cold water. Do not stir the solution.
Allow the crystals to settle at the
bottom.
• What do you observe just above the
solid crystal in the glass?
• What happens as time passes?
• What does this suggest about the
particles of solid and liquid?
• Does the rate of mixing change with
temperature? Why and how?
From the above three activities (1.3, 1.4 and
1.5), we can conclude the following:
Fig. 1.2: Estimating how small are the particles of
matter . With every dilution, though the colour
becomes light, it is still visible.
This experiment shows that just a few
crystals of potassium permanganate can
colour a large volume of water (about
1000 L). So we conclude that there must be
millions of tiny particles in just one crystal
of potassium permanganate, which keep on
dividing themselves into smaller and smaller
particles.
The same activity can be done using
2 mL of Dettol instead of potassium
permanganate. The smell can be detected
even on repeated dilution.
The particles of matter are very small –
they are small beyond our imagination!!!!
1.2 Characteristics of Particles of
Matter
1.2.1 PARTICLES OF MATTER HAVE SPACE
BETWEEN THEM
In activities 1.1 and 1.2 we saw that particles
of sugar, salt, Dettol, or potassium
permanganate got evenly distributed in water.
Similarly, when we make tea, coffee or
lemonade (nimbu paani ), particles of one type
of matter get into the spaces between particles
of the other. This shows that there is enough
space between particles of matter.
2020-21
Page 3


As we look at our surroundings, we see a large
variety of things with different shapes, sizes
and textures. Everything in this universe is
made up of material which scientists have
named “matter”. The air we breathe, the food
we eat, stones, clouds, stars, plants and
animals, even a small drop of water or a
particle of sand – every thing is matter. We
can also see as we look around that all the
things mentioned above occupy space and
have mass. In other words, they have both
mass* and volume**.
Since early times, human beings have
been trying to understand their surroundings.
Early Indian philosophers classified matter in
the form of five basic elements – the
“Panch Tatva”– air, earth, fire, sky and water.
According to them everything, living or non-
living, was made up of these five basic
elements. Ancient Greek philosophers had
arrived at a similar classification of matter.
Modern day scientists have evolved two
types of classification of matter based on their
physical properties and chemical nature.
In this chapter we shall learn about
matter based on its physical properties.
Chemical aspects of matter will be taken up
in subsequent chapters.
1.1  Physical Nature of Matter
1.1.1 MATTER IS MADE UP OF PARTICLES
For a long time, two schools of thought prevailed
regarding the nature of matter. One school
believed matter to be continuous like a block
of wood, whereas, the other thought that matter
was made up of particles like sand. Let us
perform an activity to decide about the nature
of matter – is it continuous or particulate?
Activity ______________1.1
• Take a 100 mL beaker.
• Fill half the beaker with water and
mark the level of water.
• Dissolve some salt/ sugar with the help
of a glass rod.
• Observe any change in water level.
• What do you think has happened to
the salt?
• Where does it disappear?
• Does the level of water change?
In order to answer these questions we
need to use the idea that matter is made up
of particles. What was there in the spoon,  salt
or sugar, has now spread throughout  water.
This is  illustrated in Fig. 1.1.
1.1.2 HOW SMALL ARE THESE PARTICLES
OF MATTER?
Activity ______________1.2
• Take 2-3 crystals of potassium
permanganate and dissolve them in
100 mL of water.
Fig. 1.1: When we dissolve salt in water, the particles
of salt get into the spaces between particles
of water.
* The SI unit of mass is kilogram (kg).
** The SI unit of volume is cubic metre (m
3
). The common unit of measuring volume is
litre (L) such that 1L = 1 dm
3
, 1L = 1000 mL, 1 mL = 1 cm
3
.
1
M M M M MATTER ATTER ATTER ATTER ATTER     IN IN IN IN IN O O O O OUR UR UR UR UR S S S S SURROUNDINGS URROUNDINGS URROUNDINGS URROUNDINGS URROUNDINGS
Chapter
2020-21
SCIENCE 2
• Take out approximately 10 mL of this
solution and put it into 90 mL of clear
water.
• Take out 10 mL of this solution and
put it into another 90 mL of clear water.
• Keep diluting the solution like this 5 to
8 times.
• Is the water still coloured ?
1.2.2 PARTICLES OF MATTER ARE
CONTINUOUSLY MOVING
Activity ______________ 1.3
• Put an unlit incense stick in a corner
of your class. How close do you have to
go near it so as to get its smell?
• Now light the incense stick. What
happens? Do you get the smell sitting
at a distance?
• Record your observations.
Activity ______________ 1.4
• Take two glasses/beakers filled with
water.
• Put a drop of blue or red ink slowly
and carefully along the sides of the first
beaker and honey in the same way in
the second beaker.
• Leave them undisturbed in your house
or in a corner of the class.
• Record your observations.
• What do you observe immediately after
adding the ink drop?
• What do you observe immediately after
adding a drop of honey?
• How many hours or days does it take
for the colour of ink to spread evenly
throughout the water?
Activity ______________ 1.5
• Drop a crystal of copper sulphate or
potassium permanganate into a glass
of hot water and another containing
cold water. Do not stir the solution.
Allow the crystals to settle at the
bottom.
• What do you observe just above the
solid crystal in the glass?
• What happens as time passes?
• What does this suggest about the
particles of solid and liquid?
• Does the rate of mixing change with
temperature? Why and how?
From the above three activities (1.3, 1.4 and
1.5), we can conclude the following:
Fig. 1.2: Estimating how small are the particles of
matter . With every dilution, though the colour
becomes light, it is still visible.
This experiment shows that just a few
crystals of potassium permanganate can
colour a large volume of water (about
1000 L). So we conclude that there must be
millions of tiny particles in just one crystal
of potassium permanganate, which keep on
dividing themselves into smaller and smaller
particles.
The same activity can be done using
2 mL of Dettol instead of potassium
permanganate. The smell can be detected
even on repeated dilution.
The particles of matter are very small –
they are small beyond our imagination!!!!
1.2 Characteristics of Particles of
Matter
1.2.1 PARTICLES OF MATTER HAVE SPACE
BETWEEN THEM
In activities 1.1 and 1.2 we saw that particles
of sugar, salt, Dettol, or potassium
permanganate got evenly distributed in water.
Similarly, when we make tea, coffee or
lemonade (nimbu paani ), particles of one type
of matter get into the spaces between particles
of the other. This shows that there is enough
space between particles of matter.
2020-21
MATTER IN OUR SURROUNDINGS 3
• If we consider each student as a
particle of matter, then in which group
the particles held each other with the
maximum force?
Activity ______________1.7
• Take an iron nail, a piece of chalk and
a rubber band.
• Try breaking them by hammering,
cutting or stretching.
• In which of the above three
substances do you think the particles
are held together with greater force?
Activity ______________1.8
• Take some water in a container, try
cutting the surface of water with your
fingers.
• Were you able to cut the surface of
water?
• What could be the reason behind the
surface of water remaining together?
The above three activities (1.6, 1.7 and 1.8)
suggest that particles of matter have force
acting between them. This force keeps the
particles together. The strength of this force of
attraction varies from one kind of matter to
another.
uestions
1. Which of the following are
matter?
Chair, air, love, smell, hate,
almonds, thought, cold, lemon
water, smell of perfume.
2. Give reasons for the following
observation:
The smell of hot sizzling food
reaches you several metres
away, but to get the smell from
cold food you have to go close.
3. A diver is able to cut through
water in a swimming pool. Which
property of matter does this
observation show?
4. What are the characteristics of
the particles of matter?
Particles of matter are continuously
moving, that is, they possess what we call
the kinetic energy. As the temperature rises,
particles move faster. So, we can say that with
increase in temperature the kinetic energy of
the particles also increases.
In the above three activities we observe
that particles of matter intermix on their own
with each other. They do so by getting into
the spaces between the particles. This
intermixing of particles of two different types
of matter on their own is called diffusion. We
also observe that on heating, diffusion
becomes faster. Why does this happen?
1.2.3 PARTICLES OF MATTER ATTRACT
EACH OTHER
Activity ______________1.6
• Play this  game in the field— make four
groups and form human chains as
suggested:
• The first group should hold each
other from the back and lock arms
like Idu-Mishmi dancers (Fig. 1.3).
Fig. 1.3
• The second group should hold hands
to form a human chain.
• The third group should form a chain
by touching each other with only their
finger tips.
• Now, the fourth group of students
should run around and try to break the
three human chains one by one  into
as many small groups as possible.
• Which group was the easiest to break?
Why?
Q
2020-21
Page 4


As we look at our surroundings, we see a large
variety of things with different shapes, sizes
and textures. Everything in this universe is
made up of material which scientists have
named “matter”. The air we breathe, the food
we eat, stones, clouds, stars, plants and
animals, even a small drop of water or a
particle of sand – every thing is matter. We
can also see as we look around that all the
things mentioned above occupy space and
have mass. In other words, they have both
mass* and volume**.
Since early times, human beings have
been trying to understand their surroundings.
Early Indian philosophers classified matter in
the form of five basic elements – the
“Panch Tatva”– air, earth, fire, sky and water.
According to them everything, living or non-
living, was made up of these five basic
elements. Ancient Greek philosophers had
arrived at a similar classification of matter.
Modern day scientists have evolved two
types of classification of matter based on their
physical properties and chemical nature.
In this chapter we shall learn about
matter based on its physical properties.
Chemical aspects of matter will be taken up
in subsequent chapters.
1.1  Physical Nature of Matter
1.1.1 MATTER IS MADE UP OF PARTICLES
For a long time, two schools of thought prevailed
regarding the nature of matter. One school
believed matter to be continuous like a block
of wood, whereas, the other thought that matter
was made up of particles like sand. Let us
perform an activity to decide about the nature
of matter – is it continuous or particulate?
Activity ______________1.1
• Take a 100 mL beaker.
• Fill half the beaker with water and
mark the level of water.
• Dissolve some salt/ sugar with the help
of a glass rod.
• Observe any change in water level.
• What do you think has happened to
the salt?
• Where does it disappear?
• Does the level of water change?
In order to answer these questions we
need to use the idea that matter is made up
of particles. What was there in the spoon,  salt
or sugar, has now spread throughout  water.
This is  illustrated in Fig. 1.1.
1.1.2 HOW SMALL ARE THESE PARTICLES
OF MATTER?
Activity ______________1.2
• Take 2-3 crystals of potassium
permanganate and dissolve them in
100 mL of water.
Fig. 1.1: When we dissolve salt in water, the particles
of salt get into the spaces between particles
of water.
* The SI unit of mass is kilogram (kg).
** The SI unit of volume is cubic metre (m
3
). The common unit of measuring volume is
litre (L) such that 1L = 1 dm
3
, 1L = 1000 mL, 1 mL = 1 cm
3
.
1
M M M M MATTER ATTER ATTER ATTER ATTER     IN IN IN IN IN O O O O OUR UR UR UR UR S S S S SURROUNDINGS URROUNDINGS URROUNDINGS URROUNDINGS URROUNDINGS
Chapter
2020-21
SCIENCE 2
• Take out approximately 10 mL of this
solution and put it into 90 mL of clear
water.
• Take out 10 mL of this solution and
put it into another 90 mL of clear water.
• Keep diluting the solution like this 5 to
8 times.
• Is the water still coloured ?
1.2.2 PARTICLES OF MATTER ARE
CONTINUOUSLY MOVING
Activity ______________ 1.3
• Put an unlit incense stick in a corner
of your class. How close do you have to
go near it so as to get its smell?
• Now light the incense stick. What
happens? Do you get the smell sitting
at a distance?
• Record your observations.
Activity ______________ 1.4
• Take two glasses/beakers filled with
water.
• Put a drop of blue or red ink slowly
and carefully along the sides of the first
beaker and honey in the same way in
the second beaker.
• Leave them undisturbed in your house
or in a corner of the class.
• Record your observations.
• What do you observe immediately after
adding the ink drop?
• What do you observe immediately after
adding a drop of honey?
• How many hours or days does it take
for the colour of ink to spread evenly
throughout the water?
Activity ______________ 1.5
• Drop a crystal of copper sulphate or
potassium permanganate into a glass
of hot water and another containing
cold water. Do not stir the solution.
Allow the crystals to settle at the
bottom.
• What do you observe just above the
solid crystal in the glass?
• What happens as time passes?
• What does this suggest about the
particles of solid and liquid?
• Does the rate of mixing change with
temperature? Why and how?
From the above three activities (1.3, 1.4 and
1.5), we can conclude the following:
Fig. 1.2: Estimating how small are the particles of
matter . With every dilution, though the colour
becomes light, it is still visible.
This experiment shows that just a few
crystals of potassium permanganate can
colour a large volume of water (about
1000 L). So we conclude that there must be
millions of tiny particles in just one crystal
of potassium permanganate, which keep on
dividing themselves into smaller and smaller
particles.
The same activity can be done using
2 mL of Dettol instead of potassium
permanganate. The smell can be detected
even on repeated dilution.
The particles of matter are very small –
they are small beyond our imagination!!!!
1.2 Characteristics of Particles of
Matter
1.2.1 PARTICLES OF MATTER HAVE SPACE
BETWEEN THEM
In activities 1.1 and 1.2 we saw that particles
of sugar, salt, Dettol, or potassium
permanganate got evenly distributed in water.
Similarly, when we make tea, coffee or
lemonade (nimbu paani ), particles of one type
of matter get into the spaces between particles
of the other. This shows that there is enough
space between particles of matter.
2020-21
MATTER IN OUR SURROUNDINGS 3
• If we consider each student as a
particle of matter, then in which group
the particles held each other with the
maximum force?
Activity ______________1.7
• Take an iron nail, a piece of chalk and
a rubber band.
• Try breaking them by hammering,
cutting or stretching.
• In which of the above three
substances do you think the particles
are held together with greater force?
Activity ______________1.8
• Take some water in a container, try
cutting the surface of water with your
fingers.
• Were you able to cut the surface of
water?
• What could be the reason behind the
surface of water remaining together?
The above three activities (1.6, 1.7 and 1.8)
suggest that particles of matter have force
acting between them. This force keeps the
particles together. The strength of this force of
attraction varies from one kind of matter to
another.
uestions
1. Which of the following are
matter?
Chair, air, love, smell, hate,
almonds, thought, cold, lemon
water, smell of perfume.
2. Give reasons for the following
observation:
The smell of hot sizzling food
reaches you several metres
away, but to get the smell from
cold food you have to go close.
3. A diver is able to cut through
water in a swimming pool. Which
property of matter does this
observation show?
4. What are the characteristics of
the particles of matter?
Particles of matter are continuously
moving, that is, they possess what we call
the kinetic energy. As the temperature rises,
particles move faster. So, we can say that with
increase in temperature the kinetic energy of
the particles also increases.
In the above three activities we observe
that particles of matter intermix on their own
with each other. They do so by getting into
the spaces between the particles. This
intermixing of particles of two different types
of matter on their own is called diffusion. We
also observe that on heating, diffusion
becomes faster. Why does this happen?
1.2.3 PARTICLES OF MATTER ATTRACT
EACH OTHER
Activity ______________1.6
• Play this  game in the field— make four
groups and form human chains as
suggested:
• The first group should hold each
other from the back and lock arms
like Idu-Mishmi dancers (Fig. 1.3).
Fig. 1.3
• The second group should hold hands
to form a human chain.
• The third group should form a chain
by touching each other with only their
finger tips.
• Now, the fourth group of students
should run around and try to break the
three human chains one by one  into
as many small groups as possible.
• Which group was the easiest to break?
Why?
Q
2020-21
SCIENCE 4
1.3 States of Matter
Observe different types of matter around you.
What are its different states? We can see that
matter around us exists in three different
states– solid, liquid and gas. These states of
matter arise due to the variation in the
characteristics of the particles of matter.
Now, let us study about the properties of
these three states of matter in detail.
1.3.1 THE SOLID STATE
Activity _____________ 1.9
• Collect the following articles— a pen,
a book, a needle and a piece of wooden
stick.
• Sketch the shape of the above articles
in your notebook by moving a pencil
around them.
• Do all these have a definite shape,
distinct boundaries and a fixed volume?
• What happens if they are hammered,
pulled or dropped?
• Are these capable of diffusing into each
other?
• Try compressing them by applying
force. Are you able to compress them?
All the above are examples of solids. We
can observe that all these have a definite
shape, distinct boundaries and fixed volumes,
that is, have negligible compressibility. Solids
have a tendency to maintain their shape when
subjected to outside force. Solids may break
under force but it is difficult to change their
shape, so they are rigid.
Consider the following:
(a) What about a rubber band, can it
change its shape on stretching? Is it
a solid?
(b) What about sugar and salt? When
kept in different jars these take the
shape of the jar. Are they solid?
(c) What about a sponge? It is a solid
yet we are able to compress it. Why?
All the above are solids as:
• A rubber band changes shape under
force and regains the same shape when
the force is removed. If excessive force is
applied, it breaks.
• The shape of each individual sugar or
salt crystal remains fixed, whether we
take it in our hand, put it in a plate or in
a jar.
• A sponge has minute holes, in which
air is trapped, when we press it, the air
is expelled out and we are able to
compress it.
1.3.2 THE LIQUID STATE
Activity _____________1.10
• Collect the following:
(a) water, cooking oil, milk, juice, a
cold drink.
(b) containers of different shapes. Put
a 50 mL mark on these containers
using a measuring cylinder from
the laboratory.
• What will happen if these liquids are
spilt on the floor?
• Measure 50 mL of any one liquid and
transfer it into different containers one
by one. Does the volume remain the
same?
• Does the shape of the liquid remain the
same ?
• When you pour the liquid from one
container into another, does it flow
easily?
We observe that liquids have no fixed
shape but have a fixed volume. They take up
the shape of the container in which they are
kept. Liquids flow and change shape, so they
are not rigid but can be called fluid.
Refer  to activities 1.4 and 1.5 where we
saw that solids and liquids can diffuse into
liquids. The gases from the atmosphere
diffuse and dissolve in water. These gases,
especially oxygen and carbon dioxide, are
essential for the survival of aquatic animals
and plants.
All living creatures need to breathe for
survival. The aquatic animals can breathe
under water due to the presence of dissolved
oxygen  in water. Thus, we may conclude that
solids, liquids and gases can diffuse into
liquids. The rate of diffusion of liquids is
2020-21
Page 5


As we look at our surroundings, we see a large
variety of things with different shapes, sizes
and textures. Everything in this universe is
made up of material which scientists have
named “matter”. The air we breathe, the food
we eat, stones, clouds, stars, plants and
animals, even a small drop of water or a
particle of sand – every thing is matter. We
can also see as we look around that all the
things mentioned above occupy space and
have mass. In other words, they have both
mass* and volume**.
Since early times, human beings have
been trying to understand their surroundings.
Early Indian philosophers classified matter in
the form of five basic elements – the
“Panch Tatva”– air, earth, fire, sky and water.
According to them everything, living or non-
living, was made up of these five basic
elements. Ancient Greek philosophers had
arrived at a similar classification of matter.
Modern day scientists have evolved two
types of classification of matter based on their
physical properties and chemical nature.
In this chapter we shall learn about
matter based on its physical properties.
Chemical aspects of matter will be taken up
in subsequent chapters.
1.1  Physical Nature of Matter
1.1.1 MATTER IS MADE UP OF PARTICLES
For a long time, two schools of thought prevailed
regarding the nature of matter. One school
believed matter to be continuous like a block
of wood, whereas, the other thought that matter
was made up of particles like sand. Let us
perform an activity to decide about the nature
of matter – is it continuous or particulate?
Activity ______________1.1
• Take a 100 mL beaker.
• Fill half the beaker with water and
mark the level of water.
• Dissolve some salt/ sugar with the help
of a glass rod.
• Observe any change in water level.
• What do you think has happened to
the salt?
• Where does it disappear?
• Does the level of water change?
In order to answer these questions we
need to use the idea that matter is made up
of particles. What was there in the spoon,  salt
or sugar, has now spread throughout  water.
This is  illustrated in Fig. 1.1.
1.1.2 HOW SMALL ARE THESE PARTICLES
OF MATTER?
Activity ______________1.2
• Take 2-3 crystals of potassium
permanganate and dissolve them in
100 mL of water.
Fig. 1.1: When we dissolve salt in water, the particles
of salt get into the spaces between particles
of water.
* The SI unit of mass is kilogram (kg).
** The SI unit of volume is cubic metre (m
3
). The common unit of measuring volume is
litre (L) such that 1L = 1 dm
3
, 1L = 1000 mL, 1 mL = 1 cm
3
.
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M M M M MATTER ATTER ATTER ATTER ATTER     IN IN IN IN IN O O O O OUR UR UR UR UR S S S S SURROUNDINGS URROUNDINGS URROUNDINGS URROUNDINGS URROUNDINGS
Chapter
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SCIENCE 2
• Take out approximately 10 mL of this
solution and put it into 90 mL of clear
water.
• Take out 10 mL of this solution and
put it into another 90 mL of clear water.
• Keep diluting the solution like this 5 to
8 times.
• Is the water still coloured ?
1.2.2 PARTICLES OF MATTER ARE
CONTINUOUSLY MOVING
Activity ______________ 1.3
• Put an unlit incense stick in a corner
of your class. How close do you have to
go near it so as to get its smell?
• Now light the incense stick. What
happens? Do you get the smell sitting
at a distance?
• Record your observations.
Activity ______________ 1.4
• Take two glasses/beakers filled with
water.
• Put a drop of blue or red ink slowly
and carefully along the sides of the first
beaker and honey in the same way in
the second beaker.
• Leave them undisturbed in your house
or in a corner of the class.
• Record your observations.
• What do you observe immediately after
adding the ink drop?
• What do you observe immediately after
adding a drop of honey?
• How many hours or days does it take
for the colour of ink to spread evenly
throughout the water?
Activity ______________ 1.5
• Drop a crystal of copper sulphate or
potassium permanganate into a glass
of hot water and another containing
cold water. Do not stir the solution.
Allow the crystals to settle at the
bottom.
• What do you observe just above the
solid crystal in the glass?
• What happens as time passes?
• What does this suggest about the
particles of solid and liquid?
• Does the rate of mixing change with
temperature? Why and how?
From the above three activities (1.3, 1.4 and
1.5), we can conclude the following:
Fig. 1.2: Estimating how small are the particles of
matter . With every dilution, though the colour
becomes light, it is still visible.
This experiment shows that just a few
crystals of potassium permanganate can
colour a large volume of water (about
1000 L). So we conclude that there must be
millions of tiny particles in just one crystal
of potassium permanganate, which keep on
dividing themselves into smaller and smaller
particles.
The same activity can be done using
2 mL of Dettol instead of potassium
permanganate. The smell can be detected
even on repeated dilution.
The particles of matter are very small –
they are small beyond our imagination!!!!
1.2 Characteristics of Particles of
Matter
1.2.1 PARTICLES OF MATTER HAVE SPACE
BETWEEN THEM
In activities 1.1 and 1.2 we saw that particles
of sugar, salt, Dettol, or potassium
permanganate got evenly distributed in water.
Similarly, when we make tea, coffee or
lemonade (nimbu paani ), particles of one type
of matter get into the spaces between particles
of the other. This shows that there is enough
space between particles of matter.
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MATTER IN OUR SURROUNDINGS 3
• If we consider each student as a
particle of matter, then in which group
the particles held each other with the
maximum force?
Activity ______________1.7
• Take an iron nail, a piece of chalk and
a rubber band.
• Try breaking them by hammering,
cutting or stretching.
• In which of the above three
substances do you think the particles
are held together with greater force?
Activity ______________1.8
• Take some water in a container, try
cutting the surface of water with your
fingers.
• Were you able to cut the surface of
water?
• What could be the reason behind the
surface of water remaining together?
The above three activities (1.6, 1.7 and 1.8)
suggest that particles of matter have force
acting between them. This force keeps the
particles together. The strength of this force of
attraction varies from one kind of matter to
another.
uestions
1. Which of the following are
matter?
Chair, air, love, smell, hate,
almonds, thought, cold, lemon
water, smell of perfume.
2. Give reasons for the following
observation:
The smell of hot sizzling food
reaches you several metres
away, but to get the smell from
cold food you have to go close.
3. A diver is able to cut through
water in a swimming pool. Which
property of matter does this
observation show?
4. What are the characteristics of
the particles of matter?
Particles of matter are continuously
moving, that is, they possess what we call
the kinetic energy. As the temperature rises,
particles move faster. So, we can say that with
increase in temperature the kinetic energy of
the particles also increases.
In the above three activities we observe
that particles of matter intermix on their own
with each other. They do so by getting into
the spaces between the particles. This
intermixing of particles of two different types
of matter on their own is called diffusion. We
also observe that on heating, diffusion
becomes faster. Why does this happen?
1.2.3 PARTICLES OF MATTER ATTRACT
EACH OTHER
Activity ______________1.6
• Play this  game in the field— make four
groups and form human chains as
suggested:
• The first group should hold each
other from the back and lock arms
like Idu-Mishmi dancers (Fig. 1.3).
Fig. 1.3
• The second group should hold hands
to form a human chain.
• The third group should form a chain
by touching each other with only their
finger tips.
• Now, the fourth group of students
should run around and try to break the
three human chains one by one  into
as many small groups as possible.
• Which group was the easiest to break?
Why?
Q
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SCIENCE 4
1.3 States of Matter
Observe different types of matter around you.
What are its different states? We can see that
matter around us exists in three different
states– solid, liquid and gas. These states of
matter arise due to the variation in the
characteristics of the particles of matter.
Now, let us study about the properties of
these three states of matter in detail.
1.3.1 THE SOLID STATE
Activity _____________ 1.9
• Collect the following articles— a pen,
a book, a needle and a piece of wooden
stick.
• Sketch the shape of the above articles
in your notebook by moving a pencil
around them.
• Do all these have a definite shape,
distinct boundaries and a fixed volume?
• What happens if they are hammered,
pulled or dropped?
• Are these capable of diffusing into each
other?
• Try compressing them by applying
force. Are you able to compress them?
All the above are examples of solids. We
can observe that all these have a definite
shape, distinct boundaries and fixed volumes,
that is, have negligible compressibility. Solids
have a tendency to maintain their shape when
subjected to outside force. Solids may break
under force but it is difficult to change their
shape, so they are rigid.
Consider the following:
(a) What about a rubber band, can it
change its shape on stretching? Is it
a solid?
(b) What about sugar and salt? When
kept in different jars these take the
shape of the jar. Are they solid?
(c) What about a sponge? It is a solid
yet we are able to compress it. Why?
All the above are solids as:
• A rubber band changes shape under
force and regains the same shape when
the force is removed. If excessive force is
applied, it breaks.
• The shape of each individual sugar or
salt crystal remains fixed, whether we
take it in our hand, put it in a plate or in
a jar.
• A sponge has minute holes, in which
air is trapped, when we press it, the air
is expelled out and we are able to
compress it.
1.3.2 THE LIQUID STATE
Activity _____________1.10
• Collect the following:
(a) water, cooking oil, milk, juice, a
cold drink.
(b) containers of different shapes. Put
a 50 mL mark on these containers
using a measuring cylinder from
the laboratory.
• What will happen if these liquids are
spilt on the floor?
• Measure 50 mL of any one liquid and
transfer it into different containers one
by one. Does the volume remain the
same?
• Does the shape of the liquid remain the
same ?
• When you pour the liquid from one
container into another, does it flow
easily?
We observe that liquids have no fixed
shape but have a fixed volume. They take up
the shape of the container in which they are
kept. Liquids flow and change shape, so they
are not rigid but can be called fluid.
Refer  to activities 1.4 and 1.5 where we
saw that solids and liquids can diffuse into
liquids. The gases from the atmosphere
diffuse and dissolve in water. These gases,
especially oxygen and carbon dioxide, are
essential for the survival of aquatic animals
and plants.
All living creatures need to breathe for
survival. The aquatic animals can breathe
under water due to the presence of dissolved
oxygen  in water. Thus, we may conclude that
solids, liquids and gases can diffuse into
liquids. The rate of diffusion of liquids is
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MATTER IN OUR SURROUNDINGS 5
higher than that of solids.  This is due to the
fact that in the liquid state, particles move
freely and have greater space between each
other as compared to particles in the solid
state.
1.3.3 THE GASEOUS STATE
Have you ever observed a balloon seller filling
a large number of balloons from a single
cylinder of gas? Enquire from him how many
balloons is he able to fill from one cylinder.
Ask him which gas does he have in the cylinder.
Activity _____________1.11
• Take three 100 mL syringes and close
their nozzles by  rubber corks, as
shown in Fig.1.4.
• Remove the pistons from all the
syringes.
• Leaving one syringe untouched, fill
water in the second and pieces of chalk
in the third.
• Insert the pistons back into the
syringes. You may apply some vaseline
on the pistons before inserting them
into the syringes for their smooth
movement.
• Now, try to compress the content by
pushing the piston in each syringe.
We have observed that gases are highly
compressible as compared to solids and
liquids. The liquefied petroleum gas (LPG)
cylinder that we get in our home for cooking
or the oxygen supplied to hospitals in
cylinders is compressed gas. Compressed
natural gas (CNG) is used as fuel these days
in vehicles. Due to its high compressibility,
large volumes of a gas can be compressed
into a small cylinder and transported easily.
We  come to know of what is being cooked
in the kitchen without even entering there,
by the smell that reaches our nostrils. How
does this smell reach us? The particles of the
aroma of food mix with the particles of air
spread from the kitchen, reach us and even
farther away. The smell of hot cooked food
reaches us in seconds; compare this with the
rate of diffusion of solids and liquids. Due to
high speed of particles and large space
between   them, gases show the property of
diffusing very fast into other gases.
In the gaseous state, the particles move
about randomly at high speed. Due to this
random movement, the particles hit each
other and also the walls of the container. The
pressure exerted by the gas is because of this
force exerted by gas particles per unit area
on the walls of the container.
Fig. 1.4
• What do you observe? In which case
was the piston easily pushed in?
• What do you infer from your
observations?
Fig.1.5: a, b and c show the magnified schematic
pictures of the three states of matter. The
motion of the particles can be seen and
compared in the three states of matter.
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