Group 7

• Halogens


  The elements in group 7 of the periodic table
• Halogens


  • Fluorine
  • Chlorine
  • Bromine
  • Iodine
  • Astatine
• Halogens


  • They have seven electrons in their valence shell
  • They can accept one electron to form an ion with a -1 charge
  • Moving down the group, atomic radii increases by one electron shell
  • Moving down the group, melting points, boiling points and density increase
• Moving down the group

  The reactivity of the halogens decreases
• Displacement reactions using aqueous solutions

  1. Add chlorine water to potassium chloride (no reaction)

  2. Add chlorine water to potassium bromide (bromine displaced)

  3. Add chlorine water to potassium iodide (iodine displaced)
• Displacement reactions using bromine water

  1. Add bromine water to potassium chloride (no reaction)

  2. Add bromine water to potassium bromide (no reaction)

  3. Add bromine water to potassium iodide (iodine displaced)
• No displacement reactions occur when adding iodine to the aqueous solutions
• Reaction of halogens with metals

  1. Halogens can react with certain metals to form metal halides

  2. Sodium chloride (table salt) is a common metal halide

  3. Sodium chloride can be produced from the reaction of heated sodium metal with chlorine gas
• Reaction of halogens with hydrogen

  1. Halogens can react with hydrogen gas to produce the corresponding hydrogen halide

  2. Chlorine gas and hydrogen gas can react to form hydrogen chloride
• The reactions of halogens with metals and hydrogen are highly exothermic