This deep dive covers The Three Giant Covalent Structures You Must Know within Giant Covalent Structures for GCSE Chemistry. Revise Giant Covalent Structures in Bonding & Structure for GCSE Chemistry with 21 exam-style questions and 21 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 4 of 12 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
🔬 The Three Giant Covalent Structures You Must Know
Structure:
• Each carbon atom is bonded to 4 other carbon atoms
• Forms a rigid 3D tetrahedral structure
• ALL electrons are used in bonding — none are free
Properties:
• Very hard — used in cutting tools and drill bits
• Very high melting point (~3500°C) — many strong bonds to break
• Does NOT conduct electricity — no free electrons to carry charge
• Transparent — light can pass through the regular structure
Structure:
• Each carbon atom is bonded to only 3 other carbons
• Forms flat hexagonal layers (like chicken wire)
• One electron per carbon is NOT used in bonding — these are FREE
• Layers are held together by weak intermolecular forces
Properties:
• Soft and slippery — layers can slide over each other easily
• Very high melting point — still need to break covalent bonds within layers
• DOES conduct electricity — free electrons can move along the layers
• Black and opaque — free electrons absorb light
• Used in pencils (layers rub off) and as lubricant
Structure:
• Each silicon is bonded to 4 oxygen atoms
• Each oxygen is bonded to 2 silicon atoms
• Forms a giant 3D structure similar to diamond
Properties:
• Very hard — used in glass and sand
• Very high melting point (~1700°C)
• Does NOT conduct electricity — no free electrons
Fullerenes (C₆₀) and Graphene: These are carbon structures worth knowing! Fullerenes are hollow carbon "cages" that can carry drugs in medicine. Graphene is a single layer of graphite — incredibly strong and conducts electricity. Both appear in higher tier questions.
Practice questions for Giant Covalent Structures
Why do giant covalent structures have very high melting points?
Explain why graphite conducts electricity but diamond does not.