States of Matter - Class 6

States of Matter - Class 6

ü  Matter occupies space and has mass.

ü  States of matter: The three states matter can exist are solid, liquid and gas.

ü  Solids have definite shape and volume.

ü  Liquids have definite volume but no definite shape.

ü  Gases do not have definite shape and volume.

ü  Gases have no free space unlike solids and liquids.

ü  Gases have the lowest density, no rigidity and highest mobility.

ü  Gases have least force of attraction hence the molecules of a gas can spread to occupy any volume.

ü  Solids have high density, are rigid and have no mobility.

ü  Solids cannot mix spontaneously with each other when kept in contact.

ü  Sound travels faster in solids because the molecules are tightly packed.

ü  There is no limit to the number of free surfaces that a solid can have.

ü  Liquids have only one free surface.

ü  Gases have no free surfaces.

ü  Liquids can be converted to solid on cooling.

ü  Liquids can be converted to vapour on heating or reduction of pressure.

ü  Gases can be liquefied on cooling.

ü  Gases can also be liquefied by the application of high pressure.

ü  Since liquids and gases flow, they are collectively called ‘fluids’.

ü  The higher the temperature, the faster the molecules move.

ü  Evaporation is the process of conversion of a liquid into a gas slowly from the surface of the liquid.

ü  Boiling is the process of conversion of a gas at a fixed temperature from all parts of the liquid at a fast rate.

 i. Melting point: The temperature at which a solid turns into liquid state is

  called Melting point. Example: Melting point of water is 0⁰C

ii. Boiling point: The temperature at which a liquid starts boiling point of the

  liquid. Example: The boiling point of water is 100⁰C.

iii. Sublimation is the process by which certain solids directly change

  vapour(gas) on heating. Iodine, Ammonium chloride, Naphthalene and

  Camphor.

 iv. Diffusion: The free mixing of particles of one kind with the particles of other kind.

v. Intermolecular force: The force of attraction between the molecules in a matter