Group 7

• What colour is flourine?

  pale yellow gas
• What colour is chlorine?

  pale green gas
• What colour is bromine?

  red liquid
• What colour is iodine?

  grey solid
• Atomic radius trend in G7

  Atomic radius increase down the group, atom gets larger, more shells
• IE trend in G7

  decrease down the group, atom larger, more shielding, weaker attraction between nucleus and shared electrons
• MP down G7

  increases, more electrons, Mr increases, atom gets larger so stronger VDW forces between molecules
• Bonding in G7 elements

  VDW
• How do VDW forces arise in G7?

  random movement of electrons in molecule, induces neighbouring molecules. Temporary dipoles attract
• What are oxidising agents?

  electron acceptors
• Trend of Oxidising power in G7

  decreases down the group, more shielding, less attraction from nucleus so more difficult to gain electrons
• Chlorine ion reaction with bromine salt

  bromine displaced, yellow solution
• Chlorine ions reaction with iodide salt

  Iodine displaced, brown solution
• Chlorine ions reaction with chloride salt

  no reaction, green solution
• Bromine reaction with iodide salt

  Iodine displaced, brown solution
• Bromine ions reaction with bromine salt

  no reaction, yellow solution
• What do reducing agents do?

  donate electrons
• Reducing power in g7

  increases down the group, atom gets larger, less attraction, easier for electrons to be loss
• Why is nitric acid used when testing with silver nitrate?

  to remove hydroxide or carbonate ions that may give precipitate with AgNO3
• equation for reaction of nitric acid and sodium carbonate

  2HNO3 + Na2CO3 -> 2NaNO3 + H2O + CO2
• equation for silver nitrate and sodium carbonate

  AgNO3 + Na2CO3 -> Ag2CO3 + NaNO3
• What is the role of H2SO4 in its reaction of sodium chloride ?

  proton donor
• acid base reaction with Chloride salt reaction

  NaCl + H2SO4 -> NaHSO4 + HCl
• What observation in acid base reaction of chloride salt and H2SO4

  white fumes
• redox reaction with sodium bromide and H2SO4

  2NaBr + 3H2SO4 -> Na2SO4 + 2H2O + Br2 + SO2
• Observation for NaBr reaction with con H2SO4

  orange fumes
• Oxidation half equation for Bromine salt + H2SO4

  2Br- -> Br2 + 2e-
• Reduction half equation for Bromine salt and conc H2SO4

  H2SO4 + 2H+ + 2e- -> SO2 + 2H2O
• In reaction with G7 and conc sulphuric acid which is oxidised

  the Halide ion oxidised to the halogen
• In reaction of G7 halide salt and conc sulphuric acid which reduce

  H2SO4
• redox equation for sodium iodide and conc sulphuric acid

  2NaI + 2H2SO4 -> Na2SO4 + 2H2O + I2 + SO2

  6HI + SO2 -> H2S + 3I2 + 2H2O
• products from reduction of H2SO4

  H2S, SO2, S
• Products when G7 react with silver nitrate

  AgCl, AgBr, AgI
• silver chloride reaction with dilute ammonia

  AgCl + 2NH3 -> Ag(NH3)2+ +Cl-
• When does AgCl dissolve?

  when reacting with dilute ammonia
• When does AgBr dissolve?

  When reacting with concentrated NH3
• When does AgI dissolve?

  Doesn't, too insoluble
• Disproportionation reaction

  Reaction where its substances oxidises and reduces sponatenously
• Reaction for chlorine and water

  Cl2 + H2O <-> HCl + HClO
• Reaction of chlorine and water in sunlight

  2Cl2 + 2H2O -> 4HCl + O2