group 7

• THE HALOGENS:

  • NON-METALS found in GROUP 7.
  • All halogens have SEVEN electrons in their outer shell meaning they have SIMILAR CHEMICAL properties.
  • They're DIATOMIC, meaning they exist naturally as molecules made of TWO ATOMS.
• Non-metals like halogens


  Need to gain electrons when they react
• Halogens down group 7

  • It becomes more difficult for them to gain an extra electron
  • Number of shells increases
  • Atom gets bigger
  • Less attraction between nucleus and electron being gained
  • More difficult to add electron to outer shell
• Intermolecular forces between halogen molecules


  Get stronger down the group
• TRENDS DOWN GROUP 7:

  REACTIVITY DECREASES:

  • It becomes more difficult for them to gain an extra electron, as number of shells increases and atom gets bigger
  • Less attraction between nucleus and electron being gained making it more difficult to add electron to outer shell
• TRENDS DOWN GROUP 7:

  MELTING AND BOILING POINTS INCREASE:

  • Number of ELECTRONS in the molecules INCREASES, meaning the INTERMOLECULAR FORCES between them get STRONGER.

  Meaning MORE ENERGY is needed to break the bonds.
• CHEMICAL PROPERTIES:

  • When halogens react with NON-METALS, they form SIMPLE MOLECULAR compounds with COVALENT BONDS.
  • When halogens react with METALS, they form IONIC COMPOUNDS with IONIC BONDS
• DISPLACEMENT REACTIONS:

  HALOGENS undergo DISPLACEMENT REACTIONS where a MORE REACTIVE halogen REPLACES a LESS REACTIVE halogen in a compound.
• DISPLACEMENT REACTIONS:

  • HALOGENS undergo DISPLACEMENT REACTIONS where a MORE REACTIVE halogen REPLACES a LESS REACTIVE halogen in a compound.
  • If the halogen is LESS REACTIVE, the displacement reaction will NOT occur.