Free Science Lessons: Group 7 Elements

Key Concepts

• Group 7 Elements (Halogens):
  • Also known as the halogens.
  • Consist of non-metals.
  • Have 7 electrons in their outer energy level.
  • Form diatomic molecules (molecules consisting of two atoms).

Structure and Bonding

• Atoms and Reactivity:
  • Atoms react to achieve a full outer energy level.
  • Group 7 elements react by sharing electrons, forming covalent bonds.
• Examples of Molecules:
  • Fluorine Molecule (F2):
    • Two fluorine atoms share a pair of electrons.
    • Forms a covalent bond.
  • Chlorine Molecule (Cl2):
    • Similar structure to fluorine, with a shared pair of electrons forming a covalent bond.
• Covalent Bonds:
  • Represented as a stick between two atoms.
  • Every Group 7 element forms diatomic molecules joined by covalent bonds.

Melting and Boiling Points

• Trends Down the Group:
  • Melting and boiling points increase as you move down Group 7.
• Physical States at Room Temperature (≈20°C):
  • Fluorine and Chlorine:
    • Both are gases (boiling points are below 20°C).
  • Bromine:
    • Liquid (melting point below 20°C, boiling point above 20°C).
  • Iodine:
    • Solid (both melting and boiling points above 20°C).

Relative Molecular Mass

• Increasing Down the Group:
  • Relative molecular mass increases as you move down Group 7.
  • Larger molecules as you move down the group.

Additional Resources

• Revision Workbook:
  • Available for more practice and questions.
  • Link available in the lesson for purchase.