Bonding & structure

• Metallic bonding occurs between metal atoms where they lose electrons to form positive ions surrounded by delocalised electrons.
• Covalent bonds are formed when two atoms share their outer shell electrons.
• Ionic bonding is the transfer of electrons from one atom to another.
• Suggest two reasons why 9 carat gold is often used instead of pure gold to make jewellery.

  Cost

  Pure gold is soft
• State one reaction condition that can be changed when making poly(ethene).

  Pressure
• What are the bonds between atoms in graphene?

  Covalent
• Graphite is used in pencils. Explain why

  Layers can slip as there’s no bonds between layers
• Explain why metals can be shaped.

  Made of layers which can slide over each other
• Copper metal is used in electrical appliances. Describe the bonding in a metal, and explain why metals conduct electricity.

  Lattice of positive ions with delocalised electron and electrostatic forces of attraction between the positive ions and the electrons which can move through the structure and carry charge
• This question is about sodium chloride and iodine. Describe the structure and bonding in sodium chloride.

  Giant lattice which is ionic and has electrostatic attraction. Na+ and Cl
• Explain why iodine has a low melting point.

  Simple molecules with intermolecular forces which are weak
• Explain, in terms of particles, why liquid iodine does not conduct electricity

  Iodine has no delocalised ion so can’t carry charge

   
• Aluminium ions move to the negative electrode. Explain why.

  Aluminium ions are positive so they’re attracted to the negative electrode
• Explain why graphite is very soft

  It has layers which can slide over each other as between the layers there are only weak forces
• Explain why diamond is very hard

  As each atom forms four bonds and covalent bonds are strong
• Explain why graphite conducts electricity

  As graphite has a delocalised electron which can move through the structure and carry charge
• What property of diamond makes it suitable for use on the cutting end of a drill bit?

  Hard
• Explain, why diamond is hard

  Giant structure with strong covalent bonds and each atom bonds to four other atoms
• Explain why graphite is a good conductor of electricity and why diamond does not conduct electricity.

  Graphite has a delocalised electron which can move through the structure and carry charge whereas diamond has no free electrons as they’re used for bonding
• This question is about sodium chloride and iodine. Describe the structure and bonding in sodium chloride.

  Giant lattice which is ionic and has electrostatic attraction. Na+ and Cl
• Explain why iodine has a low melting point.

   

  Simple molecules with intermolecular forces which are weak
• Explain, in terms of particles, why liquid iodine does not conduct electricity

  Iodine has no delocalised ion so can’t carry charge
• Aluminium ions move to the negative electrode. Explain why.

  Aluminium ions are positive so they’re attracted to the negative electrode

   
• Explain why graphite is very soft

  It has layers which can slide over each other as between the layers there are only weak forces
• Explain why diamond is very hard

  As each atom forms four bonds and covalent bonds are strong
•  Explain why graphite conducts electricity

  As graphite has a delocalised electron which can move through the structure and carry charge
• What property of diamond makes it suitable for use on the cutting end of a drill bit?

  Hard
• Explain, why diamond is hard

  Giant structure with strong covalent bonds and each atom bonds to four other atoms
• Explain why graphite is a good conductor of electricity and why diamond does not conduct electricity.

  Graphite has a delocalised electron which can move through the structure and carry charge whereas diamond has no free electrons as they’re used for bonding
• Explain the meaning of electrolysis

  Breakdown of electricity
• Explain why graphene is strong

  giant lattice with strong covalent bonds which require a lot of energy to break

   
• Explain why graphite is a lubricant

  Because there are weak intermolecular forces between the layers which can slide past each other

   
• Polymers are produced from crude oil. Describe the structure and bonding in a thermosoftening polymer and explain why thermosoftening polymers melt when heated.

  Chains with weak intermolecular forces which are easy to break
• Explain why copper, like many other metals, has a high melting point.

  Giant structure with positive ions and delocalised electrons and a lot of energy needed to break the bonds
• Explain why the carbon nanotube can conduct electricity.

  Delocalised electron which can carry charge