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Contents : About Matter Physical Nature of Matter Characteristics of Particles of Matter States of Matter Matter Changing its State Evaporation Multiple Choice Questions Some Interesting Pictures
About Matter Everything in this universe is made up of material which is called Matter.
Matter is anything which occupies mass and space. Each matter is a collection of lots of tiny particles.
Physical Nature of Matter Matter is made up of particles.
The particles of matter are very small –they are small beyond our imagination.
Characteristics of Particles of Matter Particles of matter have space between them. EXAMPLE : When we make tea or coffee, 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.
• Particles of matter are continuously moving. - They possess what we call the Kinetic Energy. As the temperature raises, particles move faster. So, we can say that with increase in temperature the kinetic energy of the particles also increases.
► Particles of matter attract each other. - 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.
States of Matter►Matter around us exist in three different states –(i) Solid(ii) Liquid(iii) Gas
The Solid State 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.
The Liquid State Liquids have no fixed shape but have a fixed volume.
Liquids take up the shape of the container in which they are kept.
The Gaseous State Gases are highly compressible as compared to solids and liquids.
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 greater speed. The energy supplied heat overcomes the forces of attraction between the particles. The particles leave their fixed positions and start moving freely. A stage is reached when the solid melts and is converted to liquid.
The temperature at which a solid melts to become a liquid at the atmospheric pressure 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 273.16K*. The process of melting, that is, change of solid state into liquid state is known as Fusion.
The state of matter can be changed into another state by changing the temperature.
EvaporationParticles of matter are always moving andnever at rest.
At a given temperature in any gas, liquidor solid, there are particles with differentamounts of kinetic energy.In the case of liquids, a small fraction ofparticles at the surface, having higherkinetic energy, is able to break away fromthe forces of attraction of other particlesand gets converted into vapour.
• This phenomenon of change of liquid into vapours at any temperature below its boiling point is called Evaporation.
Multiple Choice Questions►Q 1 : Liquids have(a) Fixed volume and fixed shape(b) Fixed shape and no fixed volume(c) Fixed volume and no fixed shape(d) Neither fixed volume nor fixed shape
Answer :Option :(c) Fixed volume and no fixed shape.
Q 2 : Intermolecular force of attraction is maximum in(a) Solids(b) Liquids(c) Gases(d) Plasma Membrane