Group 7

• Moving down Group Seven

  Melting and boiling points of the elements increase
• Group Seven elements are called the halogens
• All elements in Group Seven are non-metals
• Group Seven elements

  • Have seven electrons in their outer energy level
• Physical states of Group Seven elements at room temperature

  • Fluorine - gas
  • Chlorine - gas
  • Bromine - liquid
  • Iodine - solid
• Moving down Group Seven

  Relative molecular mass of the elements increases
• Group seven ions

  • Fluoride
  • Chloride
  • Bromide
  • Iodide
• Group seven elements

  Also called the halogens
• Group seven elements

  • Have seven electrons in their outer energy level
• Covalent compound


  Formed when group seven elements react with other non-metal elements
• Ionic compound

  Formed when halogens react with metals
• Halogen reacting with metal

  1. Halogen gains one electron from metal atom

  2. Halogen forms ion with negative one charge
• The name of the halogen ends with 'ide' when it forms an ion
• Group Seven Elements

  Molecules with two atoms
• All the elements in Group Seven are non-metals
• Covalent bond


  Can be represented as a stick between the two atoms
• Relative molecular mass

  Gives an idea of the size of a molecule
• Moving down Group Seven

  Relative molecular mass increases, the molecules get bigger
• Halogens

  Elements in group 7 of the periodic table
• Halogens

  • When a halogen reacts with a metal, the halogen atom gains one electron to achieve a full outer energy level
• Reactivity of halogens

  Decreases as you move down group 7 of the periodic table
• Fluorine is at the top of group 7


  Fluorine is the most reactive element in group 7
• Increased distance between outer energy level and nucleus in chlorine atom compared to fluorine atom


  Outer electrons in chlorine atom less attracted to positive nucleus
• More electrons in internal energy levels of chlorine atom compared to fluorine atom

  Greater shielding of outer electrons in chlorine atom
• Increased distance and increased shielding in atoms of halogens down group 7

  Elements get less reactive down the group
• Displacement reaction

  A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt