Summary Edexcel A level chemistry unit 2 Bonding and Structure notes (A*)

2. BONDING AND STRUCTURE




1

, 2A: Bonding
Ionic Bonding
- Strong electrostatic attraction between oppositely charged ions formed by electron
transfer
- Metal atoms lose electrons to form +ve ions
- Non-metal atoms gain electrons to form -ve ions
- giant ionic lattice structure
- stronger bonding when there are smaller ionic radius and larger charges
- Physical properties:
- High Melting Points (Strong attractive forces between ions)
- Conductor of Electricity only when in Solution or Molten (Ions free to move)
- Brittle – Moving the ions along will cause ions to be next to similar ions. Like
ions repulse, therefore layers are pushed apart


Covalent Bonding
- strong electrostatic attraction between two nuclei and the shared pair of electrons
between them
- Electrons are shared between non-metals
- Giant / simple molecular structure
- Double and Triple Bonds have a greater electron density between them so they
have a greater force of attraction between the nuclei and electrons resulting in a
shorter bond length and greater bond strength

Dative covalent bonding
- Forms when the shared pair of electrons in the covalent bond come from only
one of the bonding atoms – also referred to as a co-ordinate bond
- Common examples include (NH4)+ and (H3O)+
- represented by an arrow going from the atom that is providing the lone pair of
electrons




- A dimer is formed when two molecules covalently bond together with dative
covalent bonds e.g. Al 2Cl6