2.1 Ionic Model

Characterised by the presence of positive and negative ions

• Solid Ionic Compounds are arranged in rigid crystalline lattices ( a regular repeated three-dimensional arrangement of atoms, ions, or molecules in a metal or other crystalline solid.

  • Thus melting them requires a lot of energy due to the strong electrostatic attractions between the negative and positive ions

  • When liquid, these static ions are freed from their crystallised structure resulting in free ions called mobile ions, this results in good electrical conductors not so much when solid

  • Due to their charge they also react w/ the polar molecules of water so are often water-soluble

  • Thus, Brittle due to the structure.

  Introduction to bonds and structures

Three Bonding Models

• Ionic

• Covalent

• Metallic

Leads to four different structures

• Ionic

• Metallic

• Molecular Covalent ( Discrete group of atoms called molecules)

• Covalent network ( Continous 3D network )

Chemical bonds

• Strong attraction forces

• All bonds are from electrostatic attractions between positively-charged & negatively -charged species