Matter in our surrounding

• characteristics of matter

  1. particles of matter are vey very small .
  2. particles of matter have space between them .
  3. particles of matter are continuously moving .
  4. particles of matter attract each other.
• the intermixing of particles of two different types of matter on their own is called diffusion .
• solids have

  • definite shape
  • distinct boundaries
  • rigidity
  • fixed volume
• liquids

  • show fluidity
  • do not have a fixed shape
  • fixed volume
• gases

  • show fluidity
  • high compressibility
  • do not have a definite shape or volume
  • they occupy all the available space
• the heat supplied during the change of state, the temperature remains constant is called latent heat of fusion
• when the the temperature increases , the kinetic energy of particles increases. the particles over come the forces of attraction and the matter changes into a new state .
• the temperature at which a solid melts to become a liquid at the atmoshperic pressure is called the melting point
• the amount of heat energy required to change 1 kg of a solid into liquid at atmospheric pressure , at its melting point is called latent heat of fusion of the solid
• the temperature at which a liquid starts boiling at atmospheric pressure is called boiling point
• the amount of heat energy required to change 1 kg of a liquid into gas at atmospheric pressure , at its boiling point is called latent heat of vaporisation of the liquid.
• a change of state directly from a solid to gas without changing into liquid is called sublimation
• by applying pressure , the particles of matter can be brought together .
• the phenomenon of changing of a liquid into vapour state at any temperature below its boiling point is called evaporation
• the speed of evaporation increases with

  • increase in temperature .
  • increase in surface area .
  • increase in wind speed

  the speed of evaporation decreases with humidity in air