Matter can exist in several states depending on temperature, pressure, and interparticle forces. Scientists classify matter based on physical and chemical properties. Physically, matter can be solid, liquid, gas, plasma, or Bose-Einstein condensate (BEC). Chemically, matter can be elements, compounds, or mixtures. Solids have a definite shape and volume due to strong interparticle forces. Liquids have a definite volume but no fixed shape as particles move loosely. Gases have negligible interparticle forces, so particles are far apart and gases have no definite shape or volume. Plasma and BEC are more exotic states occurring at very high or low temperatures respectively.

1. ’

2. Anything which has mass and occupies space is known as
matter.
Matter can be identified or felt with our senses. For
example, we cannot see air but we can feel it. Our eyes can
see the physical state of matter, their physical changes and
recognize them as solid, liquid or gas. However, we can feel
heat, light, electricity, attractions emotions, beauty, sorrow,
thoughts and ideas also but the ar e not considered as
matter because they do not acquire any space and do not
acquire any space and do not have mass.

3. Modern day scientists have classified matter on the basis of physical
and chemical properties.
Physical classification
Solid
Liquid
Gas
Plasma
BEC
Chemical classification
Element
Compound
Mixture

4. Factor deciding the states of matter.
1. Temperature: As temperature increase, the kinetic energy of the particles
increases and solid matter may change into liquid and liquid may change to
gaseous state.
2. Pressure: Change in pressure can change the state of matter.
3. Interparticle space: States of matter also depend upon interparticle space.
4. The force of attraction among the particles: We have learnt that every
matter is made up of particles which may be atoms, molecules or ions. These
particles are held together through a force which is called interparticle force.

5. Solids can be defined as the state of matter in which the particles
are closely packed. One of the important features of solids under
normal conditions is that they resist change in their shape due to
strong interparicle force of attraction.
Since the particles of solid are tightly held by strong force they can
vibrate only at their position. This vibration becomes faster on
heating. To change the closely packed arrangement or to melt the
solid, very high temperature is required. Thus, melting point of solid
is high.

6. The properties of solids are as follows:
1. Definite shape and volume: Solids have definite shape and volume.
2. Ability to form lattice: Crystalline solids have well defined lattice. Lattice is
an arrangement of particles in a specific order.
3. Little cubical expansion: Solids show very little Cubical expansion or
thermal expansion as compared to liquids and gases.
4. High rigidity: The solids are generally rigid in nature and cannot change
their shape.
5. Low compressibility: Solids can not be compressed under normal
conditions.
6. Negligible kinetic energy: The particles of solids have negligible kinetic
energy because particles need space to move which is absent in solids.
7. Less or no diffusion: Solids generally do not show diffusion because their
particles have very less kinetic energy.

7. LIQUID STATE
Liquid refers to those substances which show fluidity or which
can flow but are almost incompressible and have a definite
volume. The particles in a liquid are somewhat loosely packed
and the space between the particles is slightly more than that in
solids. As liquids do not have higher kinetic energy as compared
to solids.

8. The properties of liquid are as follows:
1. No fixed shape: The liquid do not have fixed shape. They take the shape of
the container in which they are stored.
2. Fixed volume: The liquids have fixed volume because at given temperature
the interparticle space of liquid is fixed.
3. Fluidity: Liquids show fluidity. It means they can flow from height to depth or
from high pressure to low pressure.
4. Density: The liquids have lesser density than solids but have high density as
compared to gases.
5. Kinetic energy: The particles of liquids have high kinetic energy as compared
to solids.
6. Diffusion: The rate of diffusion in liquids is faster as compared to solids.

9. The state of matter having loosely
arranged particles, highest volatility and
negligible force of attraction between the
particles is called gas.

10. The properties of gases are as follows:
1. No definite shape: The gases do not have fixed shape as the particles are very far apart
because of negligible force of attraction.
2. No fixed volume: Gases do not have fixed volume because the particles have high
kinetic energy and can move in all directions.
3. Highly compressible: Gases are highly compressible because the particles are far apart
under normal conditions.
4. Thermal expansion: The gases show high thermal expansion because of very weak
interparticle force of attraction in gases.
5. Low density: The density of gases is very low. The particles of gases are very far apart.
6. Rigidity and fluidity: Intermolecular attraction is least in gases because of large
intermolecular spaces.
7. Diffusion: In gases, rate of diffusion is very high as their particles have high kinetic
energy.

11. Plasma is the fourth state of matter. At a very
high temperature, we can observe the
fourth state of matter called plasma. It is
composed of free electrons and ions. This
state of matter has very low density.

12. At an ultra-low temperature of about nano
Kelvin that is almost equal to zero Kelvin; there
exist fifth state of matter which is called BEC. In
this state, the whole matter behaves as a single
component or atom because the kinetic energy
of the atoms becomes so low that there is
hardly any vibration shown by atoms. This is
also called gaseous super fluid.