Giant Lattices (Edexcel AS Chemistry)

Ionic Lattices

• The ions form a lattice structure which is an evenly distributed crystalline structure
• Ions in a lattice are arranged in a regular repeating pattern so that positive charges cancel out negative charges
• The attraction between the cations and anions is occurring in all directions
  • Each ion is attracted to all of the oppositely charged ions around it

• Therefore the final lattice is overall electrically neutral

 

Ionic solids are arranged in lattice structures

Metallic Lattices 

• Metals form giant metallic lattices in which the metal ions are surrounded by a ‘sea’ of delocalised electrons
• The metal ions are often packed in hexagonal layers or in a cubic arrangement
• This layered structure with the delocalised electrons gives a metal its key properties

 

Layers of copper ions (the delocalised electrons are not shown in the diagram)

Covalent lattices

• Covalent bonds are bonds between nonmetals in which electrons are shared between the atoms
• Covalent compounds can be arranged in simple molecular or giant molecular lattices
  • Simple molecular lattices: iodine, buckminsterfullerene (C₆₀) and ice
  • Giant molecular: silicon(IV) oxide, graphite and diamond

Simple molecular lattices

 

Giant molecular lattices