1b - elements, compounds and mixtures

• atom

  The smallest particle that can exist of a substance
• Forming a larger particle


  Two atoms chemically combine
• Types of substances


  • Elements
  • Compounds
  • Mixtures
• Elements


  • Contains only one type of atom
• Compounds


  • Contains two or more different atoms that are chemically bonded
• Mixtures


  • Contains atoms and compounds that are NOT chemically combined to each other and can be easily separated
• Retention factor (Rf)


  The distance travelled by the dye divided by the distance travelled by the solvent
• Impurities can change the properties of a substance
• When water is impure

  The melting/freezing point will go down and the boiling point will go up
• Separation techniques


  • Simple distillation
  • Fractional distillation
  • Crystallisation
  • Paper chromatography
  • Filtration
• Filtration


  • Separates insoluble solids from liquids
• Crystallisation


  • Separates a solute from a solution by evaporation
• Simple distillation


  • Separates a solvent from a solute in a solution based on differences in boiling points
• Fractional distillation


  • Separates a mixture of liquids with different boiling points
• Liebig condenser


  A piece of equipment used in simple and fractional distillation, with an inner tube surrounded by a jacket of flowing water
• The water enters the condenser at the bottom and leaves at the top to ensure the jacket is completely full of water