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S4 Chemistry: Chemical Bonding and Structure (Paper 3)
S4 Chemistry: Chemical Bonding and Structure (Paper 3)
The third paper links structure to properties across ionic, simple molecular, giant covalent and metallic structures.
Direct answer For melting points ask what must be overcome, and for conduction ask whether charged particles can move freely.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 25 |
| Difficulty mix | Foundation 4 · Intermediate 3 · Challenge 2 · Error redo 1 |
| Chapter | Chapter: S4 Chemistry: Chemical Bonding and Structure |
| Level | Four basic, three advanced, two challenge and one error-repair item |
02 Questions (10 items)
- FoundationWhy does sodium chloride melt at a high temperature yet not conduct electricity as a solid?
- FoundationWhy is carbon dioxide a gas at room temperature with a very low melting point?
- FoundationGraphite conducts electricity but diamond does not. Explain why.
- FoundationHow many carbon atoms is each carbon bonded to in diamond, and what is the bond angle?
- IntermediateWhy is copper both a conductor and ductile?
- IntermediateMagnesium oxide melts at 2852 degrees Celsius and sodium chloride at 801. Explain the gap using ionic charge.
- IntermediateWhy does potassium nitrate conduct when molten or dissolved but not as a solid?
- ChallengeA white solid melts near 1650 degrees Celsius, does not conduct as a solid, but conducts when molten or dissolved. Identify its structure.
- ChallengeDiamond and carbon dioxide both contain strong covalent bonds. Why do their melting points differ so much?
- Error redoError repair: a student writes that metallic bonding joins a metal atom to a non-metal atom. Correct it.
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | strong ionic lattice, ions cannot move when solid | Strong attraction gives a high melting point, but in the solid the ions are locked in the lattice so nothing carries charge. |
| 2 | simple molecular structure with weak forces between molecules | The covalent bonds inside each molecule are strong but the forces between molecules are weak, so they part easily. |
| 3 | graphite has delocalised electrons, diamond has none | Both are giant covalent, but graphite has one delocalised electron per carbon in each layer while diamond has none free. |
| 4 | four, about 109.5 degrees | Each carbon joins four neighbours in a tetrahedral network with bond angles near 109.5 degrees, which makes diamond very hard. |
| 5 | delocalised electrons conduct and cation layers slide | The electron sea carries current, and the layers of cations can slide yet stay attracted, so the metal bends instead of breaking. |
| 6 | higher charges give stronger attraction, about four times | The attraction scales with the charge product, four for magnesium oxide against one for sodium chloride. |
| 7 | ions are free to move only when molten or dissolved | Conduction needs mobile charged particles, and melting or dissolving frees the ions that the solid lattice holds. |
| 8 | giant ionic structure | A high melting point with conduction only when molten is the classic ionic signature, since the ions must be released first. |
| 9 | diamond needs its whole network broken, carbon dioxide only weak forces | Every carbon in diamond is bonded to four neighbours so melting means breaking the network, while carbon dioxide molecules are held only weakly. |
| 10 | metallic bonding is between metal cations and delocalised electrons | Metallic bonding exists inside a metal only, while a metal with a non-metal normally gives ionic or covalent bonding. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
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Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.
