Chapter 3 : Matter by its Chemical Compositions

• Elements are the basic building blocks of all living and non-living matter. They cannot be broken down into simpler substances.
• Metals in the periodic table

  Appearance : Shiny

  Thermal conductivity : high

  Electrical conductivity : high

  Melting and boiling point : usually high

  Density : usually high

  Malleability and ductility : Malleable and ductile
• Non-metals in the periodic table

  Appearance : usually dull

  Thermal conductivity : low

  Electrical conductivity : low

  Melting and boiling point : usually low

  Density : usually low

  Malleability and ductility : brittle
• Properties of compounds

  1. Cannot be separated easily
  2. Do not have the same properties as its constituents
  3. Constituents area always chemically combined in a fixed porportion by mass
• 3 properties of mixtures

  1. Have similar properties to their constituents
  2. Constituents do not have a fixed porportion by mass
  3. can be seperated into its constituents easily
• Solutions

  definition ; A solution is a mixture in which one substance dissolves completely in another substance

  Solute : substance that dissolves

  Solvent : the substance in which the solute dissolves

  Solute + Solvent = solution (e.g salt + water = salt water)
• Diluted vs concentrated solution

  Diluted : contains a low percentage of dissolved solute in a given amount of solvent

  Concentrated : contains a high percentage of dissolved solute in a given amount of solvent
• Rate of dissolving

  Definition : How quickly a solute dissolves in a solvent

  A substance that dissolves completely in a solvent is soluble in the solvent

  A substance that does not dissolve in a solvent is insoluble in the solvent
• Rate of dissolving

  Factors affecting

  1. Size of solute particles
  2. Temperature of solvent
  3. rate of stirring
• Solubility

  Definition : How well as solute dissolves in a fixed volume of a particular solvent
• Suspensions

  definition : A suspension is a mixture that contains insoluble substances in a solvent

  When left undisturbed, insoluble substances in a suspension can settle to the bottom of the container and form solid deposits

  If we shine a torchlight at the suspension, light will not pass through it fully