Tetrahedral Structure
Summary: A 3D arrangement in which four bonds point away from a central atom at angles of about 109.5°. Tags: igcse chemistry keyword Created: 2026-08-06
A tetrahedral structure is a three-dimensional arrangement in which a central atom is bonded to four other atoms, with the bonds pointing towards the four corners of a tetrahedron at bond angles of approximately 109.5°. The name comes from the Greek for ‘four-faced’ (tetra = four). Because the bonds extend in all three dimensions, a tetrahedral structure has no flat layers.
The key IGCSE exam point is recognising tetrahedral structures in giant covalent substances:
- In diamond, each carbon atom is tetrahedrally bonded to four other carbon atoms by strong covalent bonds, forming a giant rigid 3D network — this is why diamond is so hard.
- In silicon dioxide (SiO₂), each silicon atom is tetrahedrally bonded to four oxygen atoms, and each oxygen atom bridges between two silicon atoms, giving a giant covalent structure (sand and quartz).
Sources
- Cambridge IGCSE Chemistry 0620 Syllabus (2023-2025), Cambridge Assessment International Education
Common Misconceptions
| Misconception | Reality |
|---|---|
| Tetrahedral structures are flat or planar | A tetrahedral arrangement is 3D — the four bonds project into three dimensions, so the structure has no layers |
| Diamond’s carbon atoms each bond to two or three others | Each carbon bonds to four others in a tetrahedral network, which is why diamond is so hard |
| Silicon dioxide has a simple molecular formula | SiO₂ is the formula of a giant covalent structure, not a small molecule — each Si bonds to 4 O atoms and each O bridges 2 Si atoms |