chapter 3

chapter 3

1. ionic bonding

   • metal and non metal
     • metals lose electrons to form a stable ion
     • non metals ions gain electrons to form stable ions
   • strong electrostatic forces of attraction between oppositley charged ions in an ionic compound
     • regular lattice structure
   • use the charges to work out the formula of the ionic compound
   • conduct electricity when molten/ in solution

2. covalent bonding

   • non metals
   • a shared pair of electrons
     • very strong as a lot of energy is needed to overcome the electrostatic forces of attraction
   • diamond and graphite
     • allotropes
       • same state but different structures
     • DIAMOND
       • each carbon atom forms 4 strong covalent bonds
       • tetrahedral structure
         • giant covalent
     • GRAPHITE
       • 3 covalent bonds between each carbon atom
         • layers
           • hexagonal structure
         • between each layer is delocalised electrons which allow the layers to slide

3. metallic bonding

   • just metals ;)
   • electrons in the outer shell become delocalized
     • +ve metal ions (cations) are held together by a sea of delocalised -ve electrons
       • strong electrostatic forces
   • mallelable and ductile
     • metal cations slide over each other if enough force is applied
   • magnesium
     • hexagonal packed structure
       • alternate layers

4. Coordinate bonding

   • 'dative covalent bond'
     • just like a covalent bond but both electrons are donated from one atom
   • to form there must be a lone pair of electrons in one atom and a vacant orbital in the other atom

5. shapes

   • linear
     • 180
     • 2 bonding pairs
   • trigonal planar
     • 120
     • 3 bonding pairs
   • tetrahedral
     • 109.5
     • 4 bonding pairs
   • trigonal bipyramidal
     • 90 and 120
     • 5 bonding pairs
   • octahedral
     • 90
     • 6 bonding pairs
   • strength of repulsion
     • lone pair : lone pair
       • lone pair : bonding pair
         • bonding pair : bonding pair