IB Chemistry HL 2.2.7 Covalent Network Structures Questions

Use exam questions to compare carbon allotropes and silicon networks through structure, delocalised electrons, strength and melting behaviour.

Exam points

Identify the three-dimensional or layered network geometry and covalent bonding around carbon or silicon atoms from a structure or diagram.
Explain graphite or graphene conductivity through mobile delocalised electrons while distinguishing them from diamond or silicon dioxide.
Compare melting point, hardness or strength by the number and strength of covalent bonds that must be broken, including weak interlayer forces where relevant.

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Study 2.2.7—Covalent network structures conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

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Ethanol has many industrial uses.

Identify three allotropes of carbon and describe their structures.

Allotropes:

diamond
graphite
fullerene
graphene;

Structures:
Diamond:
tetrahedral arrangement of (carbon) atoms/each carbon bonded to four others / $\mathrm{sp}^{3}$ and 3D/covalent network structure;
Graphite:
each carbon bonded to three others (in a trigonal planar arrangement) / $\mathrm{sp}^{2}$ and 2D / layers of (carbon) atoms;
Fullerene:
each (carbon) atom bonded to three others (in a trigonal arrangement) / $\mathrm{sp}^{2}$ and joined in a ball/cage/sphere/connected hexagons and pentagons;
Graphene:
each carbon bonded to three others (in a trigonal arrangement) / $\mathrm{sp}^{2}$ and 2D structure;

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IB Chemistry HL 2.2.7 Covalent Network Structures Questions question 1