The document explains the concept of matter, defining it as anything with mass that occupies space and describing its composition of particles (atoms or molecules). It discusses the characteristics and states of matter—solid, liquid, and gas—highlighting their properties and how they can change states through temperature and pressure variations. Additionally, it covers the process of evaporation and factors affecting it, as well as practical examples related to temperature regulation and condensation.

1. Matter

2. Matter
Anything which occupies space and have mass is
called a matter. Everything in the world is made
up of matter. Air, water, stones, food, plants,
animals whereas our universe is made up of
matter…!!
matter

3. Physical Nature of Matter- Matter is
made up of particles
Matter is made up of particles. In other words, everything is made up
small particles. These particles which make up all the matter around us
are called atoms or molecules.
Experiment
How small are these particles
The matter is made up extremely small particles which cannot be seen
even with a powerful microscope. What we actually see is an
aggregate of tiny particles. For example, even a drop of water contains
about 1021 molecules of water.
Experiment

4. 1.2 Characteristics of Particles of Matter
1.2.1 Particles of matter have space between them
Particles of matter get into the spaces between particles of the
other. This shows that there is enough space between particles of
matter. The particles of gases have large gap between each other
and the particles of liquid have gap less than that of gases and more
than that of solids between them and whereas particles of solids
have least space between them.

5. 1.2 Characteristics of Particles of Matter
1.2.2 Particles of matter attract each other
The particles of matter attract each other. In other words, particles of matter have a force
acting between them. This force keeps the particles together. The strength of this force of
attraction, however, differs from one kind of matter to other. To illustrate the strength of
this force of attraction, take an iron nail, a piece of chalk and a rubber band. Try to break
each one of them by hammering, cutting or stretching. You will observe that it is most
difficult to break the iron nail, somewhat easier to break a piece of chalk and easiest to
break a rubber band. Thus, the particles of iron rod are held together by the strongest
force followed by the piece of chalk while particles of rubber band are held together by
the strongest force followed by the piece of chalk while particles of rubber band are held
together by the weakest forces of attraction.

6. 1.3 States of Matter
The Solid STaTe
 Properties –
i. Solids have definite shape.
ii. Solids have distinct boundaries.
iii. Solids have fixed volume.
iv. Solids have negligible compressibility.
v. Solids have tendency to maintain their shape when subjected to outside force.
vi. Solids may break under force but it is difficult to change their shape, so they are rigid.
Types of Solids
1. Crystalline Solids (diamond, copper sulphate etc.)
2. Amorphous Solids (rubber, sponge etc.)

7. 1.3 States of Matter
The liquid STaTe
 Properties –
i. Liquids have don’t have a fixed shape. They attain the shape of the container in
which they are kept.
ii. Liquids flow and change their shape, so they are not rigid but can be called fluid.
iii. Solids, gases and liquids can diffuse into liquids.
iv. Solids don’t have tendency to maintain shape when subjected to outside force.
v. Liquids have a definite volume at a given temperature.
vi. Liquids are almost incompressible.

8. 1.3 States of Matter
The GaSeouS STaTe
o Properties-i.
Gases do not have definite shape.
ii. They do not have a definite volume too.
iii. Gases also have a tendency to flow as liquids do. Therefore, they are also
considered as fluids.
iv. Gases diffuse very easily among other substances at a considerable rate.
v. The interspace between their molecules is maximum while the attraction force is the
minimum. Therefore, the gas molecules occupy all the space available to them.
vi. The density of gases is minimum.
vii. Gases exert pressure on the walls of the container, in which they are filled. This
pressure is due to the random movement of particles and hitting against the walls of
the container.

9. 1.4 Can Matter Change its State
1.4.1 effecT of chanGe of TemperaTure
On increasing the temperature of solids, the kinetic energy of
the particles increases. Due to the increase in kinetic energy, the
particles start vibrating with great speed. The energy supplied by
heat overcomes the forces of attraction between the particles .
The particles leave their fixed positions and start moving more
freely. A stage is reached when the solid melts and is converted
to a liquid.
Melting Point : The temperature at which a solid melts to become liquid at
the atmospheric temperature is called its melting point. The melting point of a
solid is an indication of the strength of the force of attraction between its
particles. The melting point of ice is 273.16 K.
Fusion : The process of melting, that is, change of solid state into liquid
states also known as fusion.

10. 1.4 Can Matter Change its State
1.4.1 effecT of chanGe of TemperaTure
 When a solid melts, its temperature remains the same, so where
does the heat energy go?
During the experiment of melting, that the temperature of the
system does not change after the melting point is reached, till all
the ice melts. This happens even though we continue to heat the
beaker, that is, we continue to supply heat. This heat gets used up
in the changing the state by overcoming the forces of attraction
between the particles. As this heat is absorbed by ice without
showing any rise in temperature. It is considered that it gets
hidden into the contents of the beaker and is known as latent
heat.
Latent heat of fusion : The amount of heat energy that is required to
change 1 kg of a solid into liquid at atmospheric pressure at its melting
point is known as latent heat of fusion.

11. 1.4 Can Matter Change its State
1.4.1 EffEct of changE of tEmpEraturE
When we supply heat energy to water, particles start moving even
faster. At a certain temperature, a point is reached when the
particles have enough energy to brake free from the forces of
attraction of each other. At this temperature the liquid starts
changing into gas.
Boiling Point : The temperature at which a liquid starts boiling at the
atmospheric temperature is known as its boiling point. Boiling is a bulk
phenomenon. Particles from the bulk of the liquid gain enough energy to
change into the vapour state.
For water this temperature is 372 K { 100°C = 273+100 = 373 K }
Particles in steam, that is, water vapour at 373 K (100°C ) have
more energy than water at the same temperature. This is because
particles in steam have absorbed extra energy in the form of latent
heat of vaporisation.

12. 1.4 Can Matter Change its State
1.4.1 EffEct of changE of tEmpEraturE
The state of matter can be changed into another by changing the
temperature.
We have learnt that substances around us change state from solid
to liquid and from liquid to gas on application of heat. But there
are some that change directly from solid state to gaseous state
and vice versa without changing into the liquid state.

13. 1.4 Can Matter Change its State
1.4.1 EffEct of changE of prEssurE
The difference in various states of matter is due to the difference in the
distances between the constituent particles. Applying pressure and
reducing temperature can liquefy gases.
Solid carbon dioxide is stored
under high pressure. Solid carbon
dioxide gets converted directly to
gaseous state without coming into liquid
state. This is the reason that solid carbon
dioxide is also known as dry ice.
Thus, we can say that pressure and temperature determine the state of a
substance, whether it will be solid, liquid or gas
By applying pressure, particles of matter
can be brought close together

14. Evaporation
 Particles of matter are always moving and are never at rest. At a given
temperature in any gas, liquid or solid there are particles with different
amounts of kinetic energy. In the case of liquid, a small fraction of
particles at the surface, having higher kinetic energy, is able to break
away from the forces of attraction of other particles phenomenon of
converted into vapour. This phenomenon of change of a liquid into
vapours at any temperature below its boiling point is called evaporation.

15. Factors affecting Evaporation
Temperature: By rising temperature, the rate of evaporation also
increases.
Surface Area: Rate of evaporation can be effected by increasing
and decreasing the surface area.
Humidity: When humidity increases the rate of evaporation
decreases.
Speed of wind: Wind need kinetic energy to flow. If the speed
of wind will be more than the kinetic energy and temperature will be
also more, so the rate of evaporation will be also more.
Nature of liquid: The rate of evaporation also depends on the
nature of liquid, i.e. the interparticle force of attraction.

16. Why should we wear cotton clothes in
summer?
 During summer, we perspire more because of the mechanism of
our body which keeps us cool. We know that during evaporation,
the particles at the surface of the liquid gain energy from the
surroundings or body surface and change into vapour. The heat
energy equal to the latent heat of vaporisation is absorbed from the
body leaving the body cool. Cotton, being a good absorber of
water helps in absorbing the sweat and exposing it to the
atmosphere for easy evaporation.

17. Why do we see water droplets on the
outer surface of a glass containing ice-cold
water?
Let us take some ice-cold water in a tumbler. Soon we will see
water droplets on the outer surface of the tumbler. The water
vapour present in air, on coming in contact with the cold glass of
water, looses energy and get converted to liquid state, which we
see as water droplets.

18. Please watch in Slideshow