 It is something which has mass, occupy space and and can be
realized by the sense organs.


 Made up of very small particles (unimaginable).
 Inter-molecular space
 They posses kinetic energy (continuously moving)
 Intermolecular force (attract each other at varying degree on
the basis of matter)



 Greek word “atomos” meaning indivisible
 Smallest particle of an element that may or may not exist
 Atoms of different masses and chemical properties.


 group of two or more atoms that are chemically bonded together.
 Smallest particle of an element or a compound that is capable of
independent existence
 It does not take part in chemical reaction.


 The substances have definite mass, volume and shape. For
e.g., wood, table, pen, book, etc.
 Because of the presence of strong intermolecular forces,
these are highly dense.


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?


 The substances have no fixed shape but have a fixed volume.
 They take up the shape of the container in which they are
kept for e.g., water, oil, milk etc.
 Intermolecular forces are no longer strong enough to hold the
particles together.


No fixed shape and volume (depends on the shape and
size of the container). For e.g. air, o2 etc.
Weak intermolecular forces = expands more when
intermolecular space is very large = highly compressible

Interconversion of states of matter:

Fusion: The process of melting i.e., change of solid state into
liquid state.
Vaporization: The process in which a liquid substance
changes into a gas rapidly on heating.
Condensation: It is the process in which gas changes into
the liquid state or liquid changes to solid state i.e.,

Sublimation: Process used for those solids which convert
directly into vapors on heating without converting into
liquid phase and the vapors upon cooling back the solid.
(sublimates: dry ice)

Evaporation: The phenomenon of change of a liquid into
vapours at any temperature below its boiling point is called
The rate of evaporation depends upon the surface area
exposed to the atmosphere, the temperature, the humidity
and the wind speed.
EVAPORATION CAUSES COOLING: The particles of liquid
absorb energy from the surrounding to regain the energy
lost during evaporation. This absorption of energy from the
surroundings make the surroundings cold. E.g. earthen
pots, coolers etc.

Melting point: The temperature at which a solid starts to
melt to become a liquid at the atmospheric pressure.

Boiling point: The temperature at which a liquid starts
boiling at the atmospheric pressure

Latent heat: latent means “hidden”. It is the amount of
heat absorbed or released by a substance undergoing a
change of state

Latent heat of fusion: Amount of heat energy that is
required to change 1 kg of a solid into liquid at
atmospheric pressure at its melting point

Latent heat of vaporization: Heat energy required to
change 1 kg of liquid to gas at the atmospheric pressure at
its boiling point.


On heating the solid, kinetic energy of the particles
increases. (vibration)
The energy supplied by the heat overcomes the forces of
Due to this, the particles leave their fixed position and
start moving freely.
A stage is reached, when solid melts and starts to convert
into liquid.
Same process for liquid to gas

Effect of change of pressure

 By increasing pressure and reducing temperature, gas
can be converted into liquid and liquid into solid.

Other states of matters


It consists of super energetic and super excited particles (in
the form of ionized gases). For e.g., fluorescent tube
(helium or some other gas), neon sign bulbs (neon gas)
The gas gets ionized, i.e., gets charged when electrical
energy flows through it, creates a plasma glowing inside the
tube or bulb.
The Sun and the stars glow because of the presence of
plasma (very high temperature) in them


In 1920, Indian physicist Satyendra Nath Bose
(calculations ) and Albert Einstein (prediction)
In 2001, Eric A. Cornell, Wolfgang Ketterle and Carl E.
Wiemsan of USA received the Nobel prize in physics for
achieving “Bose-Einstein condensation”.
Formed by cooling a gas of extremely low density, about
the density of normal air, to super low
temperatures (absolute zero).

chemical clasification of matter

 A pure substance consists of a single type of particles.
 If something is pure, it means that all the constituent
particles of that substance are the same in their
chemical nature.

Element: A basic form of matter that cannot be broken
down into simpler substances by any physical chemical
substances. It can be solid like Iron (Fe), Gold (Au),
liquid like mercury (Hg), and gas like helium (He),
oxygen (O)
Compound: It is composed of two or more elements,
chemically combined with one another in a fixed
proportion. For e.g. water (H2O), Salt (NaCl).

A compound can be broken down into its elements by
chemical or electrochemical reactions, but not by any
physical process.

Mixture: it is constituted by more than one kind of pure
form of matter, known as a substance. It does not have
constituents in fixed proportions. The mixtures can be
separated into their constituents by simple physical
Homogeneous Mixture: these mixtures have a
uniform composition throughout. E.g., salt or sugar in
water, vinegar etc.
Heterogeneous Mixture: these mixtures contain
physically distinct parts and have non-uniform
composition. E.g., soil in water, oil and water


Heterogeneous mixture’s separating methods: hand picking,
sieving, filtration etc.

Homogeneous mixture’s separating methods :
Evaporation: already discussed above
Centrifugation: A process that involves use of centrifugal force
for sedimentation. The denser particles are forced to the bottom
and the lighter particles stay at the top when spun rapidly. E.g.
blood and urine samples, washing machine, butter from cream
Separation funnel: immiscible liquids separate out in layers
depending upon their densities. (used for separating the mixture
off oil and water.)

 Sublimation: discussed above
Chromatography: it is used for those solutes that dissolves
in the same solvent. It is used to separate colors in dye;
pigments from natural colors etc.
 Distillation: it is based on the difference in the boiling
points of the liquids in the given mixture. The two opposite
processes i.e. vaporization and condensation are involved
in this process.
 Crystallization: this method is used to purify solids. It is a
process that separates a pure solid in the form of its
crystals from a solution.

Law of chemical combinations

Law of conservation of Mass (Antoine Lavoisier):

It states that matter can neither be created nor be
Total mass of reactants = total mass of products

Law of multiple proportions (Dalton):

If two elements combine to form more than one
compound. Compounds of differing mass ratios of the
same elements are found, but they will have different properties.

Law of definite proportions (Joseph Proust):

It states that a given compound always contains exactly
the same proportion of elements combined in a fixed
ratio by weight (mass) irrespective of the source.
For example:
C + O2 = CO2
CH4 + 2O2 = CO2 + 2H2O
CaCo3 = CO2 + CaO


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