.

• Solid

  • Particles are closely packed
  • Orderly arranged (lattice)
  • Strong
  • Particles do not move at all
  • Only vibrate
  • Fixed volume and shape
  • Difficult to compress
• Liquid

  • Still touching each other but some gaps
  • Strong, but less than solid
  • Move in and out of each other
  • Fixed volume and shape (take the shape of container)
  • Difficult to compress
• Gas

  • Far apart
  • Weak
  • Particles move freely to all directions
  • Not fixed volume and shape
  • Easy to compress
• Melting

  Change the state of a substance from solid to liquid.
• Freezing

  Change the state of a substance from liquid to solid.
• Condensation

  Change the state of a substance from gas to liquid.
• Boiling

  Change the state of a substance from liquid to gas at fixed temperature.
• Evaporation

  Change the state of a substance from liquid to gas at variable temperature.
• Sublimation

  Change the state of a substance from solid to gas directly without turning into liquid state.
• Deposition

  Change the state of a substance from gas to solid directly without turning into liquid state.
• Melting point

  The temperature at when the solid starts to melt

  e.g. melting point of ice = 0'C
• Freezing point

  The temperature of which the liquid starts to freeze

  e.g. freezing point of water = 0'C
• Boiling point

  The temperature of which the liquid starts to boil

  e.g. boiling point of water = 100'C
• Diffusion


  Spreading out of particles from higher concentration to the lower concentration due to random motion.
• Rate of diffusion depends on

  1. Temperature
  2. molecular mass
• The rate of diffusion is proportional to the temperature.
• The rate of diffusion is inversely proportional to the molecular mass.
• Atom

  Smallest particle that can enter into a chemical combination
• Molecular

  Two or more atoms joined together
• Element

  A substance which cannot be broken down into simpler substance by physical or chemical means.
• Compound

  Two or more elements chemically combined in a fixed proportion.

  e.g. H2O, CO2
• Mixture

  Various substances mixed in any proportion

  No chemical reaction
• Alloy

  Steel > iron mix with carbon

  Brass > copper mix with zinc

  Bronze > copper mix with tin
• Salt solution - Nacl + H2O
• Nitrogen - 78% > making ammonia, in car tyres, to make fertilizers, food packaging
• Oxygen - 21% > in steel production, breathing aid to hospital patient, oxyacetylene flame in welding
• Argon - 0.9% > light bulb
• Carbon dioxide - 0.04 > in fire extinguisher, in frizzy drinks
• Three types of mixture

  Mixture of element

  Mixture of compounds

  Mixture of elements and compounds
• Separating mixtures

  1. Filtration
  2. Crystallisation
  3. Simple distillation
  4. Fractional distillation
  5. Chromatography
• Filtration - to separate insoluble solids from a liquid.

  e.g. sand from a mixture of sand and water
• Residue - the solids left on the filter paper after filtration
• Filtrate - the liquid pass through the funnel into the flask
• Crystallisation - soluble solids(solute) from a solution
• Solute - a substance which can dissolve in a solvent
• solvent - a liquid in which a solute dissolve
• solution - a mixture of solute and solvent
• Simple distillation

  To separate solvent from a solution

  e.g. water from salt solution
• Soluble salts

  • All potassium, sodium, lithium, and ammonium salts
  • All nitrates
  • Most of the chlorides

  except - sliver chloride, lead ll chlorides

  • Most of the sulfates

  except - silver sulfate, lead ll surlfate, barium sulfate, calcium sulfate (slightly soluble)
• Most of the hydroxides and carbon mix are insoluble

  except - potassium, sodium, lithium, ammonium