2C - Bonding and structure

     1)    This question is about copper:

            a)    Describe metallic bonding.  You may wish to use a diagram. [2]

                                

            Labelled diagram [1]  electrostatic forces of attraction between delocalised electrons and metal ions [1]

            b)    How does a metal conduct electricity? [1]

            The electrons are free to move [1]

 

     2)    This question is about the salt sodium chloride, NaCl:

            a)    Discuss the conductivity of NaCl compounds.  Explain your answer.  [5]

                 Solids do not conduct [1]  as the ions are held in a fixed position [1]

            Dissolved [1] and molten [1] as the ions are free to move [1]

            b)    With the aid of a diagram explain the solubility of sodium chloride in water.  [4]

                 Water is a polar molecule [1] 

            These are attracted to the ions, weaken the ionic bonds pulling them away from the lattice [1]

 

     3)    Complete the following table for the following substances:  [20]

 

    NaCl SiO2 Br2 NH3
  Structure Giant Ionic Giant covalent Simple covalent Simple covalent
  Melting point High High Low Low
  Electrical conductivity aq / molten No No No
  Solubility in water Yes No No Yes
  Solubility in non polar solvent No No Yes No

 

            Each box correct [1]  x 20