1. 1
   An electrician uses copper wire to carry electricity around a house because copper conducts electricity extremely well. The electrician also notices that the copper wire can be bent around corners without snapping.

   (a)

   Which statement explains why copper, like other metals, conducts electricity so well?

   [1 mark]

   • ACopper contains delocalised electrons that are free to move throughout the structure and carry charge
   • BCopper atoms are held together by weak intermolecular forces that allow electrons to pass through easily
   • CCopper is a giant ionic structure with mobile ions
   • DCopper atoms have no electrons in their outer shell

   (b)

   The electrician bends the copper wire around a corner and notices that it bends easily without breaking. Which statement explains why copper can be bent into shape?

   [1 mark]

   • ACopper has no fixed structure so it can be reshaped freely
   • BCopper contains weak covalent bonds that break and reform easily
   • CCopper ions repel each other, allowing the structure to stretch
   • DThe layers of positive metal ions in the structure can slide over each other while remaining held together by the delocalised electrons

   (c)

   Explain, in terms of structure and bonding, why copper both conducts electricity well and can be bent into shape.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A metalworker hammers a sheet of aluminium into a curved shape to make part of an aircraft wing, without the metal cracking. Later, the same aluminium sheet is used to conduct heat away from a hot engine component.

   (a)

   Which statement explains why aluminium can be hammered into shape?

   [1 mark]

   • AAluminium is a simple molecular substance that reshapes when heated
   • BAluminium atoms are only weakly attracted to each other, so they separate easily under force
   • CThe layers of aluminium ions can slide over each other while delocalised electrons continue to hold the structure together
   • DAluminium ions are arranged randomly, allowing free movement in any direction

   (b)

   The same aluminium sheet is used to conduct heat away from a hot engine component. Which statement best explains why aluminium conducts heat well?

   [1 mark]

   • AAluminium atoms vibrate faster than atoms in other substances
   • BThe delocalised electrons in the metallic structure are free to move and transfer thermal energy quickly throughout the metal
   • CAluminium contains air pockets that trap and release heat
   • DAluminium has a low melting point, which makes it conduct heat well

   (c)

   Explain, in terms of structure and bonding, why aluminium can be hammered into shape without cracking and also conducts heat efficiently away from the engine component.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student compares a block of iron (a metal) with a block of silicon dioxide (a giant covalent structure). She hits each block with a hammer. The iron dents and changes shape, while the silicon dioxide shatters into fragments.

   (a)

   Explain, in terms of structure and bonding, why iron can be reshaped by hammering while silicon dioxide shatters instead.

   [3 marks]

   (b)

   The student then tests both blocks for electrical conductivity in the solid state. The iron conducts electricity well, but the silicon dioxide does not conduct at all. Explain this difference in terms of the electrons present in each structure, and explain why iron continues to conduct electricity even after being reshaped by hammering.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A cookware designer is choosing a metal to make the base of a frying pan, which must conduct heat efficiently from the hob to the food and be able to be pressed into a curved shape during manufacturing without cracking. She selects stainless steel.

   (a)

   Describe, in terms of structure and bonding, why a metal such as stainless steel is well suited to both of these requirements.

   [6 marks]

   (b)

   The designer considers, but rejects, a giant covalent ceramic material for the pan base instead of stainless steel, even though the ceramic can also withstand very high temperatures. Explain, in terms of structure and bonding, why the ceramic material would not be suitable for the manufacturing process that presses the pan base into its curved shape, even though it might handle the cooking temperatures well.

   [6 marks]

   Total for question 4: 12 marks

End of questions