Separating Techniques

• Filtration, crystallisation + evaporation

  1. Physical method

  2. Doesn't produce new substances

  3. No chemical reaction occurring
• Filtration


  • Separates the components of a mixture
  • Separates an insoluble solid from a liquid
• Insoluble


  Doesn't dissolve in solvent
• Soluble


  • Compound dissolves
  • Indicated by (aq) label
  • If not soluble, use (s) label
• Soluble group 1 metals


  • Na+
  • K+
  • Li+
• Filtration procedure

  1. Grab a funnel and funnel paper

  2. Put funnel paper in funnel and fit in beaker

  3. Pour mixture into funnel

  4. Liquid will seep through

  5. Solid residue will remain in filter paper
• Compounds formed from non-metals have very different properties from the original elements
• Elements


  • Iron (magnetic metal)
  • Sulfur (yellow powder)
• Compound


  • Iron sulfide (dull grey lump)
• Ca(OH)2


  Calcium atom, 2 oxygen atoms, 2 hydrogen atoms
• RAM (Relative Atomic Mass)


  (Isotope abundance x mass no) + 100
• Isotopes


  Same protons, different neutrons
• 2NaOH


  2 sodium, 2 oxygen, 2 hydrogen
• Molecules


  • 2 or more atoms held together by chemical bonds
  • e.g. O2, CO2, H2O
• Electron energy levels


  Lowest energy levels are always filled first, closest to nucleus
• Alpha particles


  • Positively charged
  • Most went straight through, so most of atom is empty space
  • Some were deflected, so nucleus must have positive charge
  • Few bounced straight back, so most of mass is concentrated in nucleus