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S4 Chemistry: Chemical Bonding and Structure (Paper 1)
S4 Chemistry: Chemical Bonding and Structure (Paper 1)
The first paper identifies the three bond types, then practises ion electron counts and simple formulae.
Direct answer Check whether the partners are metals or non-metals: transfer gives ionic bonding, sharing gives covalent bonding, and a metal on its own uses metallic bonding.
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)
- FoundationWhich type of bond is present in sodium chloride?
- FoundationWhich type of bond is present in a water molecule?
- FoundationWhat holds the copper atoms together in a piece of copper metal?
- FoundationA sodium atom has 11 electrons. How many electrons does the Na+ ion have?
- IntermediateA chlorine atom has 17 electrons. Give the electron count and arrangement of the Cl- ion.
- IntermediateMagnesium with 12 electrons bonds with oxygen with 8. Give the electron count of each ion.
- IntermediateHow many pairs of electrons are shared between carbon and each oxygen in carbon dioxide, and in the whole molecule?
- ChallengeGive the formula of the compound of Al3+ and O2-, and show the charges cancel.
- ChallengeHow many pairs of electrons are shared in an N2 molecule and why is nitrogen so unreactive?
- Error redoError repair: a student claims that any transfer of electrons makes a covalent bond. Correct this.
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | ionic bond | Sodium donates an electron to chlorine, so the ions Na+ and Cl- are held by electrostatic attraction. |
| 2 | covalent bond | Both hydrogen and oxygen are non-metals, so they share electron pairs in a covalent bond. |
| 3 | metallic bonding between cations and delocalised electrons | The metal cations are held by the sea of delocalised electrons that their outer electrons form. |
| 4 | 10 | One electron is lost, so 11 minus 1 leaves 10 electrons arranged 2,8. |
| 5 | 18 electrons, 2,8,8 | One electron is gained, 17 plus 1 is 18, the same arrangement as argon. |
| 6 | Mg2+ 10, O2- 10 | Magnesium loses two electrons and oxygen gains two, so both end with ten electrons and the neon arrangement 2,8. |
| 7 | two pairs per C=O, four pairs in total | Carbon dioxide is O double bond C double bond O, so two pairs per double bond and four pairs in all, that is eight shared electrons. |
| 8 | Al2O3 | Two aluminium ions and three oxide ions give 2 times plus 3 plus 3 times minus 2, which is zero. |
| 9 | three pairs, a strong triple bond | The triple bond needs a large amount of energy to break, so nitrogen is unreactive at room temperature. |
| 10 | transfer gives ionic bonding; covalent bonding shares electron pairs | Transfer and sharing are different routes: transfer gives ions, sharing gives molecules. |
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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