chemistry chap 8

• What is a disproportionation reaction?

  Oxidation and reduction of the same element
• Examples of disproportionation reaction?

  1. water treatment - reaction of chlorine and water
  2. bleach - reaction of chlorine and cold, dilute, aqueous sodium hydroxide
• Describe the colours and states of the halogens (first 4)

  1. flourine - pale yellow gas
  2. chlorine - pale yellow-green gas
  3. bromine - red-brown liquid
  4. iodine - crystalline grey-black solid
• Explain the trend in boiling points of halogens?

  • boiling points increase as we go down the group
  • because London forces increase - due to increased number of electrons, relative mass, and increasing size
• Explain the trend of electronegativity for group 7 elements?

  • electronegativity decreases as you go down the group

  1. nuclear charge increases
  2. atomic radius increases
  3. electron shielding increases
• colour change of halogens in aqueous organic solutions

  1. water

  • chlorine - pale green
  • bromine - orange
  • iodine - brown

  2. cyclohexane

  • chlorine - pale green
  • bromine - orange
  • iodine - violet