Group 7

• what are the physical qualities of fluorine

  Gas at RTP , pale yellow
• what are the physical qualities of chlorine

  gas at RTP , yellow green , pale yellow in water , yellow green in cyclohexane
• what are the physical qualities of bromine

  gas at RTP , red/brown , red in water , reddish in cyclohexane
• what are the physical properties of iodine

  solid at RTP , shiny and grey , violet in water , pink in cyclohexane
• do melting points and boiling points increase or decrease down group 7

  increase as you go down the group
• why does the boiling and melting points increase as you go down group 7

  - there is more shells as you go down making it easier to attract an electron

  - shielding - more shielding as you go down so its easier to attract an electron due to weaker London forces

  - distance - larger distance from nucleus so its easier to attract an electron due to weaker London forces
• what is disproportionation

  a redox reaction in which the same element is both oxidised and reduced
• what is the chlorine reaction in water

  Cl2 + H2O —> HCL + HClO
• what is the reaction between chlorine and sodium hydroxide solution

  Cl2 ( g ) + 2NaOH ( aq ) —> NACl ( aq ) NaClO ( aq ) + H2O
• what are the qualitative tests for chlorine

  add HNO3 - a false positive due to dissolved CO2

  add AgNO3 - forms a white ppt

  should dissolve in dilute NH3
• what are the qualitative tests for bromide ions

  Add N03 - false positive due to dissolved CO2

  add AgNO3 - cream ppt

  Dissolves in concentrated NH3
• What are the qualitative tests for iodide ions

  Add NO3 - a false positive due to CO2

  Add AgNO3 - pale yellow precipitate

  insoluble in ammonia solutions
• what is the test for sulphate ions SO4 2-

  A false positive with HNO3 and AgNO3

  add barium chloride solution - white ppt forms
• what are the test for carbonate ions CO3 2-

  add HNO3 - bubbles and fizzed

  false positive in AgNO3 AND barium chloride solution