# Giant covalent structure

A huge network of atoms joined by strong covalent bonds. These substances have very high melting points.

Chemistry (school) · Part 03: Bonding and structure · Card 7 of 9 · Last updated 2026-10-19

## Analogy

It is like a giant net in which every knot is tied tight to its neighbours.

## In practice

Diamond, graphite and silicon dioxide (sand) are giant covalent structures.

## Practice

### Flashcards

- **Why does graphite conduct electricity?** Each carbon atom has a free electron that can move through the layers.

### Interview questions

**Explain why diamond is very hard but graphite is soft, even though both are made only of carbon.**

- Diamond: each carbon bonded to four others
- Strong covalent bonds in all directions
- Graphite: each carbon bonded to three others in layers
- Weak forces between layers let them slide

## Questions people ask

### Why does silicon dioxide have a high melting point?

Silicon dioxide, the main substance in sand, is a giant network of silicon and oxygen atoms. Each atom is held by strong covalent bonds in all directions. Melting needs many of these bonds to break, which takes a great deal of energy. It melts at over 1,600 degrees Celsius.

### What is diamond used for?

Diamond is the hardest natural substance, so it is used to cut and grind. Drill bits and saw blades are tipped with it. It is also used in jewellery because it is clear and sparkles. Its strong covalent bonds in every direction give this hardness.

## Related concepts

- [Allotrope](https://studyvisually.com/learn/science/chemistry-school/chemistry-school-part-3/chemistry-school-part-3-concept-8)
- [Covalent bond](https://studyvisually.com/learn/science/chemistry-school/chemistry-school-part-3/chemistry-school-part-3-concept-3)
- [Simple molecule](https://studyvisually.com/learn/science/chemistry-school/chemistry-school-part-3/chemistry-school-part-3-concept-6)

Web page: https://studyvisually.com/learn/science/chemistry-school/chemistry-school-part-3/chemistry-school-part-3-concept-7
Study this card in the app: https://studyvisually.com/app/learn?category=chemistry-school&card=chemistry-school-part-3-concept-7