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S4 Chemistry: Atomic Structure (Paper 2)
S4 Chemistry: Atomic Structure (Paper 2)
Ten original questions link arrangement to the periodic table: sulfur with sixteen electrons gives 2,8,6 for period three group six, aluminium loses three electrons to become Al3+, and a chloride ion holds eighteen electrons in 2,8,8. The middle items work back from an ion with eighteen electrons to calcium at atomic number twenty, use mass number 40 with twenty neutrons, and compare Na+ with F-, both having ten electrons in 2,8. One item turns 2,8,8,1 into potassium, and the paper ends with the notation error of writing the sodium ion as Na+1.
Direct answer Read shells as the period and outer electrons as the group, add or subtract the charge to recover protons, and check the charge notation last.
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: Atomic Structure |
| Level | Four basic, three advanced, two challenge and one error-repair item |
02 Questions (10 items)
- FoundationSulfur has atomic number 16 and mass number 32. Give its protons, neutrons and electrons.
- FoundationWrite the electron arrangement of sulfur with sixteen electrons and state its period and group.
- FoundationAluminium with atomic number 13 loses three electrons. Give the ion symbol and arrangement.
- FoundationHow many electrons does a chloride ion have and how are they arranged?
- IntermediateAn ion X2+ has eighteen electrons. Give the atomic number and the element.
- IntermediateAn atom has mass number 40 and twenty neutrons. Give its protons and electrons.
- IntermediateNoble gases are in group 0. How many electrons usually fill their outermost shell?
- ChallengeCompare the electron count and arrangement of Na+ and F-.
- ChallengeAn atom has the arrangement 2,8,8,1. Give its atomic number, period and group.
- Error redoError repair: a student writes the sodium ion as Na+1. What is the correct notation?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | 16 protons, 16 neutrons, 16 electrons | A neutral atom has sixteen electrons, and thirty-two minus sixteen gives sixteen neutrons. |
| 2 | 2,8,6; period 3, group 6 | Shells give the period and outermost electrons give the group, so three shells and six electrons mean period three, group six. |
| 3 | Al3+, arrangement 2,8 | From 2,8,3 it loses the three outer electrons, carries three positive charges and is written Al3+. |
| 4 | 18 electrons; 2,8,8 | A chlorine atom with seventeen electrons gains one for eighteen, filling the arrangement 2,8,8. |
| 5 | atomic number 20, calcium | The ion has lost two electrons, so the atom had twenty, which is calcium at atomic number twenty. |
| 6 | 20 protons and 20 electrons | Forty minus twenty gives twenty protons, and a neutral atom has the same number of electrons. |
| 7 | 8 electrons, or 2 for helium | Group zero has a full outer shell of eight electrons, which is why they are unreactive; helium fills one shell with two. |
| 8 | both have 10 electrons in the arrangement 2,8 | Sodium loses one of its eleven electrons and fluorine gains one on nine, both ending with ten electrons in 2,8. |
| 9 | atomic number 19, period 4, group 1 | The electrons total nineteen across four shells, so period four with one outer electron means group one. |
| 10 | Na+ | The charge sits at the upper right with the number first and the sign after, and one is omitted, so Na+. |
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.
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.
