Giant Covalent Structures
Giant covalent structures are made of non-metal atoms bonded together in a huge network. All the atoms are linked by strong covalent bonds, resulting in very high melting points and hardness.
What is a giant covalent structure?
- A giant covalent structure (also called a macromolecule) contains millions of atoms
- Atoms are joined by strong covalent bonds in a regular lattice
- Unlike simple molecules, there are no weak intermolecular forces
Properties of giant covalent structures
Property | Explanation |
Very high melting and boiling points | Lots of energy needed to break strong covalent bonds |
Usually hard and rigid | All atoms are bonded into a strong 3D structure |
Do not conduct electricity | Except for graphite – most have no free electrons |
Insoluble in water | Bonds are too strong to be broken by water molecules |
Examples of giant covalent structures
Diamond (carbon)
- Each carbon atom forms 4 covalent bonds
- Forms a 3D rigid structure
- Very hard, used in cutting tools
- Does not conduct electricity
Graphite (carbon)
- Each carbon atom forms 3 covalent bonds
- Layers of hexagons with delocalised electrons
- Soft and slippery – layers slide over each other
- Conducts electricity (delocalised electrons can move)
Silicon dioxide (SiO₂)
- Found in sand
- Each silicon atom bonded to 4 oxygen atoms
- Strong, hard, and insoluble
- Used in glass and ceramics
Questions
- What type of bonding holds atoms in a giant covalent structure?
- Why is diamond so hard?
- Why does graphite conduct electricity but diamond does not?
- What structure is found in sand?
- Why do giant covalent structures have high melting points?
Summary
- Giant covalent structures are made of atoms bonded in a huge network
- They have very high melting and boiling points due to strong covalent bonds
- Most are hard and don’t conduct electricity
- Graphite is an exception – it conducts electricity and is slippery
- Diamond, graphite, and silicon dioxide are common examples