Group 7 - Halogens

• As you go down Group 7:

  • Reactivity decreases
  • Melting and boiling points increases
  • Relative atomic mass increases
• Halogens "jobs":

  • Fluorine - poisonous yellow gas, very reactive
  • Chlorine - poisonous green gas, less reactive
  • Bromine - volatile red-brown liquid, poisonous
  • Iodine - dark grey solid, which can form poisonous purple vapour
• Reactions of Halogens:

  1. Covalent bonds ~ formed with non-metals to form molecular compounds
  2. Ionic compounds ~ formed when they react with metals
  3. More reactive halogens can displace less reactive ones
  4. e.g. Cl + 2KBr → Br + 2KCl (chlorine is more reactive than bromine)
• Characteristics of group 7;

  • Coloured vapours.
  • Diatomic molecules.
  • Form ionic salts with metals.
  • Form molecular compounds with non-metals.