Halogens

• Trend in melting and BP down group

  -increases down group

  -molecules become larger as they have more electrons

  -larger VDW between molecules

  -more energy needed
• trend in electronegativity


  -as u descend the group, e neg decreases

  -atomic radii increases due to increasing shells so nucleus less able to attract bonding pair of e-
• reducing agent halogens


  -increasing power as reducing agents descending the group

  -greater tendency to donate e

  -ions get bigger and easier for outer nucleus to be given away
• fluorine and chloride reaction with H2SO4

  -not strong enough reducing agents to reduce S in h2so4

  -no redox reactions occur

  -only acid base reactions

  -WHITE STEAMY FUMES OF HCL/HF EVOLVED
• bromide reaction with H2SO4

  -stronger reducing agents (has 2 steps)

  reduces sulfur in h2so4 from +6 to +4 in SO2

  WHITE STEAMY FUMES OF HBR AND ORANGE FUMES OF BR ARE EVOLVED AND COLOURLESS/ACIDIC GAS SO2
• Reaction of cl/br/i in AQ with cold NaOH

  Cl2+2NaOH—> NaCl + NaCLO +H2O

  -mixture of NACL AND NACLO used as bleach
• chlorine and water reaction products

  -HCLO

  -HCL
• NaClO

  sodium chlorate (I)
• NaClO3

  sodium chlorate(V)
• K2SO4

  potassium sulfate (VI)
• K2SO3

  Potassium sulfate (IV)
• Observations of Iodide and Sulfuric acid SO2

  colourless acidic gas
• Observations of Iodide and Sulfuric acid HI

  white steamy fumes
• Observations of Iodide and Sulfuric acid I2

  black solid and purple fumes
• Observations of Iodide and Sulfuric acid S

  yellow solid
• Observations of Iodide and Sulfuric acid H2S

  gas with bad egg smell