CLASS 6TH | CHEMISTRY | MATTER | REVISION NOTES

Anything which occupies space and has mass is called “Matter”.
Eg. Oxygen, air, silver, steel
Characteristics of matter:
Things around us are composed of different kinds of materials. In the same material same
type of molecules are found such as in case of ice, water molecules are present.
(1)Matter occupies the space:
The volume is the amount of space occupied by the material.
(2) Matter has mass:
Any kind of material visible and invisible, has certain amount of matter in it called as “mass”
Structure and composition of matter:
Matter is made up of very very small particles in it.
These particles which make up the matter are atoms, ions and molecules
.
• Atoms :
Atoms consist of nucleus which is positive charge at centre and electrons which possesses
negative charge as in cloud around it.
In case of sodium and helium they presence in combine form as lack of individual existence
to form molecules.
• Molecules:
These are the smallest distinct units into which a pure matter can be divided. They represent
the chemical and composition property of matter.
Combination of two or more atoms result in formation of molecule. Combine atoms may be
of one kind or different. Water is made up of hydrogen and oxygen where hydrogen molecule
is made up of two hydrogen atoms.
• Ions:
Ions may be positive or negative with respect to atoms or group of atoms. Atom or group of
atom transformed to form ions when they lose or gain the one or more electron.
Eg. Sodium ion (Na+
) , Chlorine ion (Cl-
)

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States of matter:
On the basis of physical property namely temperature the matter is classified into
(A)Solid -ice
(B)Liquid- water
(C)Gas- air
By changing the temperature one can easily change the states of matter.
The characteristic of matter is depend upon the arrangement of atoms or molecules inside
the matter.
The molecules of matter are held together by force of attraction between them, called as
intermolecular force of attraction. And the space between molecules are called as
intermolecular space.
These arrangement of particles inside the matter decides whether is exist as solid , liquid or
gas.
Solid states:
Characteristic by structural rigidity and with definite shape and volume. Molecules are tightly
packed due to strong intermolecular force in between solid particles .
Properties of solid :

1. Have tightly packed particle
2. Possess fixed shape and fixed volume
3. Solid do not show fluidity
4. Cannot be compressed much
   Liquid state:
   Characterised by the change in its shape but resistivity towards change in its volume.
   They are less tightly packed as compared to solid. Within the liquid molecules are moving one
   position to another, indicating fluidity.
   Properties of liquid:
5. Have loosely packed particles.
6. Have fixed volume but do not have fixed shape , take the shape of container in which
   they are place
7. Liquid flow easily.
8. Liquid cannot be compressed much

Gaseous state:
State of matter which characteristic by its capacity to change its shape and size.
They are very loosely packed as compare with solid and liquid arrangement of molecules.
They do possess weak intermolecular forces which result in molecules are far apart.
They are free to move.
Properties of gases:

1. Particle within the gas , are loosely packed.
2. They take the whole shape and volume of the container in which they are kept as
   result of neither of fixed volume nor a fixed shape.
3. Gases easily flow.
4. Gases can be compressed with ease into small volumes.
   Effect of arrangement on the basis of their property:
   The property shown by matter is depend upon the arrangement present in it.
   o SOLID:
   In solid structure the molecules are closely packed, in such way that their position is almost
   fixed. Hence retained shape and volume. The intermolecular space is very small as the result
   of greater intermolecular force of attraction between solid particles.
   Application of heat onto solid, brings the extra energy to molecules and they begin to move
   apart from their position finally resulting in the state change from solid to liquid.
   o LIQUID:
   Intermolecular space in the liquid particle is more comparable to solid as result of which due
   to the weaker intermolecular force. That’s why the molecules are free to move.
   Hence liquid does not possess definite shape and it takes the shape of container.
   On heating liquid changes into vapour which is gaseous state. This is because on heating liquid
   molecules get or acquires energy and start moving with higher speed and near the surface or
   boundary get escape from the liquid and produce vapour.
   o GASES:
   Characteristic by fast moving particle with average speed of 1600km/hr.
   The intermolecular space is wide because of very weak intermolecular force of attraction
   between gas molecules.
   The molecular force of attraction is depend upon the density but due to low density the force
   is non-existence. Hence gas neither has shape nor have fixed volume.
   On cooling the density goes on increase result into establishment of intermolecular force
   which brings molecule closer and gas get converted into liquid.