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IGCSE · Practice questions · Giant covalent structures and metallic bonding

Structure explains use.

Six original Cambridge-style questions on giant structures: diamond, graphite, silicon(IV) oxide and metals, linking each property back to the bonding.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Keep these straight

Link every property to a bond.

01
Recall
[2 marks]

Describe the structure and bonding in diamond.

  • A giant covalent structure of carbon atoms. ✓
  • Each carbon atom is covalently bonded to four other carbon atoms (tetrahedrally). ✓
02
Explain
[4 marks]

Use the structure of graphite to explain why it is used as a lubricant and as an electrode.

  • Graphite has layers of hexagons in which each carbon atom is covalently bonded to three others. ✓
  • The forces between the layers are weak, so the layers slide over each other: a lubricant. ✓
  • Each carbon atom has one delocalised electron, ✓
  • which can move through the structure and carry charge, so graphite conducts: an electrode. ✓
03
Explain
[2 marks]

Explain why diamond does not conduct electricity but graphite does.

  • In diamond all four outer electrons of each carbon are used in covalent bonds, so there are no free electrons. ✓
  • In graphite each carbon uses only three electrons in bonding, leaving one delocalised electron per atom that can move. ✓
04
Analysis
[3 marks]

(Extended) In silicon(IV) oxide each silicon atom is bonded to four oxygen atoms and each oxygen atom to two silicon atoms. Explain how this gives the formula SiO2, and predict two physical properties.

  • Each Si is surrounded by 4 O, but each O is shared between 2 Si, so there are 4 ÷ 2 = 2 O atoms for every Si atom: SiO2. ✓
  • Very high melting point (many strong covalent bonds to break). ✓
  • Hard, and does not conduct electricity (no free electrons or ions). ✓
05
Recall
[2 marks]

(Extended) Describe metallic bonding.

  • A lattice of positive metal ions in a sea of delocalised electrons. ✓
  • Metallic bonding is the electrostatic attraction between the positive ions and the delocalised electrons. ✓
06
Explain
[3 marks]

(Extended) Copper is used for electrical wiring. Use its metallic bonding to explain why copper conducts electricity and why it can be drawn into wires.

  • Copper contains delocalised electrons that are free to move through the structure and carry charge. ✓
  • The layers of positive ions can slide over each other, ✓
  • while the delocalised electrons keep attracting them, so the metallic bonding is not broken and the metal is ductile. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.