2.3 Group 7 - Yr12

• first ionisation energy decreases down the group as atomic radius increases so outershell further away from nucleus so increase shielding so therefore decrease attraction between shared pair and nucleus
• boiling point increases as you go down the group because IMFs (VDWs) are breaking and these forces are stronger down the group as polarisation of electron cloud increases
• atomic radius increases down the group as more electron shells
• oxidising power decreases down the group as harder to gain an electron as increase atom size and increase shielding
• reducing power increases down group as ions get larger so increase shielding and attraction between nucleus and outer electron decreases
• chlorine + water word equation:

  • Cl2(g) + H2O(l) -><- HCl(an) + HClO(aq)
• chlorine + water word equation in sunlight

  • Cl2(g) + H2O(l) -> 4HCl(an) + O2(g)
• chlorine + dilute sodium hydroxide word equation

  • Cl2(g) + 2NaOH(an) -> NaCl(an) + NaClO(aq) + H2O(l)
• NaClO is a powerful weed killer
• Chlorine is added to drinking water to sterilise it as it kill bacteria and makes it safe to drink, chlorine is toxic but benefits outweigh risks
• AgNO3

  • added to Cl2, Br2, I2 and a precipitate of insoluble silver halide is produced
  • dilute nitric acid added before AgNO3 to prevent formation of other insoluble silver salts
  • Ag+(aq) + X-(aq) -> AgX(s)
• reation of aqueous halides and silver nitrate and ammonia (chloride)

  • adding AgNO3(aq) = white ppt
  • effect of adding dilute and concentrated ammonia = ppt dissolves to form colourless solution
• relations of aqueous halides and silver nitrate and ammonia (bromide)

  • adding AgNO3(aq) = cream ppt
  • adding dilute ammonia = no observable change
  • adding concentrated ammonia = ppt dissolves to form colourless solution
• reactions of aqueous halides and silver nitrate and ammonia (iodide)

  • adding AgNO3(aq) = yellow ppt
  • adding dilute and concentrated ammonia = no observable change
• appearances and solubilities of halogen compounds (chloride)

  • state and colour at 25 degrees = white solid
  • soluble in water
  • colourless in aqueous solution
  • not soluble in hexane
• appearances and solubilities of halogen compounds (bromide)

  • state and colour at 25 degrees = white solid
  • soluble in water
  • colourless in aqueous solution
  • not soluble in hexane
• appearances and solubilities of halogen compounds (iodide)

  • state and colour at 25 degrees = white solid
  • soluble in water
  • colourless in aqueous solution
  • not soluble in hexane
• appearance and solubility of halogens (chlorine)

  • state and colour at 25 degrees = pale green gas
  • colour of aqueous solution = green
  • colour of solution in hexane = pale yellow
  • more soluble in hexane
• appearance and solubility of halogens (bromine)

  • state and colour at 25 degrees = red brown liquid
  • colour of vapour = orange brown
  • colour of aqueous solution = orange
  • colour of solution in hexane = yellow orange
  • more soluble in hexane
• appearance and solubility of halogens (iodine)

  • state and colour at 25 degrees = solid grey
  • colour of vapour = purple
  • colour of aqueous solution = orange red
  • colour of solution in hexane = purple
  • more soluble in hexane