Cambridge IGCSE Chemistry (workbook) · Ch.4 continued, pp.34–35

Chemistry — Ch.4 (pp.34–35: giant structures & metallic bonding)

Graded 2026-06-18 · Sys4Ethan (Claude Opus 4.8 vision, human-verified)

57%

✅ Correct 4 ◐ Partial 3 ✗ Needs fixing 0 ○ Not attempted 0 Total 7

To fix & review (3)Qp34 · Q3(a) describe structures Qp35 · Q2 metallic passage Qp35 · Q3 metallic diagram

Qp34 · Q2(d–f) SiO₂ ✓ Correct compound / structure / formula

(d) compound — two different elements chemically combined ✓; (e) giant covalent structure ✓; (f) $\text{SiO}_2$ ✓.

Qp34 · Q3(a) describe structures ◐ Partial diamond + SiO₂ structure

You described diamond (each C covalently bonded to 4 C).

Try this → Also describe silicon(IV) oxide: each silicon is covalently bonded to 4 oxygen atoms (and each oxygen to 2 silicons), giving the tetrahedral giant structure.

Qp34 · Q3(b) common properties ✓ Correct giant covalent properties

Very high melting points + hard solids — both right.

Qp34 · Q3(c) why diamond is hard ✓ Correct structure → property

Each carbon bonded to 4 others by strong covalent bonds in a giant 3D network ✓.

Qp34 · Q3(d) use of diamond ✓ Correct uses

Cutting ✓.

Qp35 · Q2 metallic passage ◐ Partial spot & correct errors

Found 3 errors: protons→electrons, non-metal→metal ions, localised→delocalised. Good.

Try this → There's one more error — a metallic bond is the electrostatic ATTRACTION (not repulsion) between the positive metal ions and the sea of delocalised electrons.

Qp35 · Q3 metallic diagram ◐ Partial labelled diagram

Try this → You drew the arrangement, but the question asks for a LABELLED diagram — label the positive metal ions and the 'sea' of delocalised electrons.

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