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S4 Chemistry Bonding, Paper 2: properties of ionic and molecular structures
S4 Chemistry Bonding, Paper 2: properties of ionic and molecular structures
Ten graded items linking bonding to conductivity, melting point, molar mass and electron arrangement.
Focus Classify the structure first, then reason about conductivity and melting point, and only then calculate.
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: Bonding and Structure |
| Level | Four basic, three advanced, two challenge and one error-repair item |
02 Questions (10 items)
- FoundationPotassium loses one electron when it reacts with chlorine. Write the formula of the product.
- FoundationHow many pairs of electrons are shared between the two atoms in an oxygen molecule?
- FoundationWhy does copper conduct electricity?
- FoundationWhy does graphite conduct electricity while diamond does not?
- IntermediateSodium oxide melts at a higher temperature than sodium chloride. Explain using ionic charges.
- IntermediateSilicon dioxide has a giant covalent structure. State two of its physical properties.
- IntermediateFind the molar mass of aluminium oxide, Al2O3, with Al as 27.0 and O as 16.0.
- ChallengeIodine monochloride is a liquid at room temperature with a melting point near 27 degrees, while sodium chloride melts at 801 degrees. Explain the difference.
- ChallengePotassium has atomic number 19. Write the electron arrangement of the K+ ion by shells.
- Error redoA student says diamond does not conduct because carbon has no valence electrons. Give the correct explanation.
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | KCl | Potassium loses one electron to form K+ and chloride is Cl-, so they combine one to one as KCl. |
| 2 | Two pairs, four electrons in total | Each oxygen atom needs two more electrons, so two pairs are shared and a double bond forms. |
| 3 | It has delocalised electrons that move freely | The valence electrons are not held by any one atom and move freely through the whole piece of metal. |
| 4 | Graphite leaves one electron delocalised per carbon; diamond uses all four in bonds | Graphite bonds each carbon to three others and leaves the fourth electron free, while diamond uses all four in bonds. |
| 5 | The charge product is 2 x 1 in Na2O against 1 x 1 in NaCl, so the attraction is twice as strong | The charge product in sodium oxide is two rather than one, so the electrostatic attraction in the lattice is stronger. |
| 6 | Very high melting point and great hardness; it does not conduct in either state | Strong covalent bonds run through the whole structure, so it is hard, melts very high and carries no free charge. |
| 7 | 102.0 g mol^-1 | Two aluminium atoms give 54.0 and three oxygen atoms give 48.0, so the total is 102.0. |
| 8 | ICl is a simple molecular substance with weak forces between molecules; NaCl is a giant ionic lattice | ICl is a simple molecule held by weak van der Waals forces, while sodium chloride is a giant ionic lattice held by strong electrostatic attraction. |
| 9 | 2, 8, 8 | Potassium is 2, 8, 8, 1 and loses its outer electron, leaving the same arrangement as argon. |
| 10 | Carbon has four valence electrons, but in diamond all four are used in covalent bonds | Carbon has four valence electrons, but in diamond all of them are locked in covalent bonds, so none can move. |
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.
