Bonding

• What is the structure of diamond?


  Macromolecular

  Giant covalent lattice, each C atom forms 4 strong covalent bonds to other C atoms
• Why does diamond have a high melting/boiling point?


  Each C atom bonded to 4 other C in giant covalent lattice - strong covalent bonds take a lot of energy to break
• Why does diamond not

  conduct electricity?


  No delocalised electrons free to move
• What is the structure of graphite?


  Macromolecular

  Giant covalent lattice, layers of carbon atoms bonded to 3 others with weak van der Waals' forces between the layers
• Why does graphite conduct electricity?


  Each Carbon atom contributes one electron to the delocalised sea of electrons which are free to move throughout the structure
• Why does graphene have a high melting / boiling point ?


  Each C atom bonded to 3 other C in giant covalent lattice - strong covalent bonds take a lot of energy to break
• What is the structure of SiO2 ?


  Macromolecular / giant covalent lattice
• What type of compounds have ionic bonding?


  Metal + non-metal
• What is ionic bonding?


  Many strong electrostatic attractions between oppositely charged ions in a lattice
• What is the structure of an ionic compound such as NaCl ?


  Giant ionic lattice with many strong electrostatic attractions between oppositely charged ions
• Why do ionic compounds have a high melting point?


  Many strong electrostatic attractions between oppositely charged ions take a lot of energy to break
• Why do ionic compounds e.g. NaCl conduct electricity when molten or in solution ?


  Ions free to move and carry charge
• Why don't ionic compounds e.g. NaCl conduct electricity when solid ?


  Ions not free to move
• Why are ionic compounds brittle ?


  Layers of lattice slide which causes like charges to align - and repel each other
• Which 2 factors increase the strength of ionic bonding (and so m.p.) ?


  Smaller ion and greater charge

  (both have greater charge density)
• What is metallic bonding?


  Strong electrostatic attractions between positive ions and delocalised electrons in a lattice
• Why do metals have a high melting point?


  The many strong electrostatic attractions between positive ions and delocalised electrons in a lattice require a lot of energy to break
• Why are metals malleable?


  Layers (of positive ions) can slide
• What is an alloy ?


  A mixture of metals
• Why are alloys stronger than pure metal ?


  Ions of different size distort the layers so the layers cannot slide
• What factors increase the

  melting point of a metal ?


  Smaller ion

  Greater charge

  Greater charge density so greater SABPIDEL
• 2 b.p shape and angle


  Linear 180 degrees

  
• 3 b.p 0 l.p. shape and angle


  Trigonal planar 120 degrees

  
• 2 b.p 1 l.p. shape and angle


  Bent 118 degrees
• 4 b.p 0 l.p. shape and angle


  Tetrahedral 109.5 degrees

  
• 3 b.p 1 l.p. shape and angle


  Trigonal pyramid 107.5 degrees

  
• 2 b.p 2 l.p. shape and angle


  Bent 105.5 degrees

  
• 4 b.p 1 l.p. shape and angle


  See-saw 88 and 118 degrees

  
• 3 b.p 2 l.p. shape and angle


  T-shaped 86 degrees

  
• 2 b.p 3 l.p. shape and angle


  Linear 180 degrees
• 6 b.p 0 l.p. shape and angle


  Octahedral 90 degrees

  
• 5 b.p 1 l.p. shape and angle


  Square Pyramidal 88 degrees
• 4 b.p 2 l.p. shape and angle


  Square Planar 90 degrees

  
• 3 b.p 3 l.p. shape and angle


  T-shaped 84 degrees
• 2 b.p 4 l.p shape and angle


  Linear 180 degrees
• For a molecule with no l.p: explain the shape of (molecule)


  (Molecule) has X b.p and 0 l.p

  Electron pairs repel each other as far away as possible

  B.p repel each other equally
• For a molecule with 1 l.p: explain the shape of (molecule)


  (Molecule) has X b.p and 1 l.p

  Electron pairs repel each other as far away as possible

  L.p - b.p repulsion is greater than b.p - b.p repulsion
• For a molecule with 2 or more l.p: explain the shape of (molecule)


  (Molecule) has X b.p and X l.p

  Electron pairs repel each other as far away as possible

  L.p - l.p repulsion is greater than l.p - b.p repulsion which is greater than b.p - b.p repulsion
• What type of elements form covalent bond?


  Non-metals
• What is a covalent bond?


  A pair of shared electrons