What are the three types of covalent substance, based on their structure?
- Substances made of small, separate molecules
- Substances made of very large molecules
- Giant covalent structures
AQA GCSE Combined Science: Trilogy (8464) — Chemistry — Higher · 5.2.1.4
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What are the three types of covalent substance, based on their structure?
What does each chemical formula represent in a substance made of small, separate molecules?
One discrete molecule.
What is the structure of a polymer molecule?
A long covalent chain of many atoms, made from repeating units.
How does bonding in a giant covalent structure differ from bonding in a molecular substance?
Covalent bonds extend through a continuous network rather than forming separate molecules.
What are two examples of giant covalent structures?
Diamond and silicon dioxide.
What diagram features identify a giant covalent structure?
A repeating, extended network of atoms joined by covalent bonds, rather than separate individual molecules.
How does diamond appear in a structure diagram?
A three-dimensional network of carbon atoms.
How does graphite appear in a structure diagram?
Layers of carbon atoms bonded in extended sheets.
How does silicon dioxide appear in a structure diagram?
A network of silicon and oxygen atoms linked throughout the structure.
What attraction holds bonded atoms together in a covalent bond?
The shared electrons are attracted to the nuclei of both atoms.
What does the strength of a covalent bond mean for the energy needed to break it?
A relatively large input of energy is needed to overcome the attraction and break the bond.
Are covalent bonds strong in small molecules, polymer molecules and giant covalent structures?
Yes. Covalent bonds are strong in all three.