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Flip to reveal answersWhat is a giant covalent (network) solid?
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All 12 Flashcards — Covalent network structures
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Question
What is a giant covalent (network) solid?
Answer
A continuous lattice of atoms joined by **covalent bonds** in every direction — there are **no separate small molecules**.
Question
Why do all giant covalent solids have very high melting points?
Answer
Melting requires breaking **many strong covalent bonds**, which needs a large amount of energy.
Question
What is an allotrope?
Answer
Different structural forms of the **same element** — e.g. diamond and graphite are both pure carbon.
Question
How is each carbon bonded in diamond?
Answer
To **four** other carbons in a rigid **3-D tetrahedral** network.
Question
Why is diamond hard?
Answer
Its **rigid 3-D framework** of strong covalent bonds cannot be pushed out of shape.
Question
Why does diamond not conduct electricity?
Answer
All **four** outer electrons of each carbon are used in bonds, so there are **no delocalised electrons** to carry charge.
Question
How is each carbon bonded in graphite?
Answer
To **three** others in flat **layers**; the **fourth** electron is **delocalised**.
Question
Why does graphite conduct electricity?
Answer
The **delocalised electrons** between the layers are free to move and carry charge.
Question
Why is graphite soft?
Answer
**Weak forces** between the layers let the **layers slide** over each other (the covalent bonds within a layer stay strong).
Question
Name the four giant covalent solids you must know.
Answer
**Diamond**, **graphite** (carbon allotropes), **silicon (Si)** and **silicon dioxide (SiO_{2})**.
Question
Why does a giant covalent solid melt far higher than a molecular solid?
Answer
Giant covalent → break **strong covalent bonds**; molecular → only overcome **weak intermolecular forces**.
Question
Diamond vs graphite conductivity — why the difference?
Answer
Diamond uses all 4 electrons in bonds (**no** delocalised e⁻ → no conduction); graphite has **1 delocalised** e⁻ per carbon (conducts).
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Full study notes for Covalent network structures
Topic 2.2 hub
The covalent model
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