Unit 2 · Inorganic Chemistry (AS & A Level)
The Complete Cambridge International AS & A Level Chemistry (9701) Guide · Cambridge International AS & A Level Chemistry (9701)Unit 2 · Inorganic Chemistry (AS & A Level)
- The Complete Cambridge International AS & A Level Chemistry (9701) Guide
- Cambridge International AS & A Level Chemistry (9701)
- 4 sections
Cambridge International does not publish a per-unit weighting for this exam. Exam structure (official): AS Level: Multiple Choice (75 min, 40 questions, 31%) · AS Level Structured Questions (75 min, 46%) · Advanced Practical Skills (120 min, 23%); A Level: Multiple Choice (75 min, 40 questions, 15.5%) · AS Level Structured Questions (75 min, 23%) · Advanced Practical Skills (120 min, 11.5%) · A Level Structured Questions (120 min, 38.5%) · Planning, Analysis And Evaluation (75 min, 11.5%). Be ready to carry the same unit skills and representations into a complete answer on every paper. Inorganic Chemistry begins with particles and observations. Distinguishing an ion from an atom keeps charge, color, and reactivity attached to the correct species.
- How Cambridge International AS & A Level Chemistry (9701) assesses this Cambridge International publishes no per-unit percentage for Cambridge International A Level Chemistry; Paper 1 accounts for 31% of the AS Level total and 15.5% of the A Level total. · AS Level: Multiple Choice (75 min, 40 questions, 31%) · AS Level Structured Questions (75 min, 46%) · Advanced Practical Skills (120 min, 23%) | A Level: Multiple Choice (75 min, 40 questions, 15.5%) · AS Level Structured Questions (75 min, 23%) · Advanced Practical Skills (120 min, 11.5%) · A Level Structured Questions (120 min, 38.5%) · Planning, Analysis And Evaluation (75 min, 11.5%) · show the model with a particle-level comparison of two substances, a reagent-condition-observation-inference table, balanced redox half-equations with electron cancellation, a bracketed complex-ion formula with overall charge, a wavelength or absorbance graph tied to an energy change, a sequence of catalytic steps that sums to the overall reaction
- Key skills Periodicity of Physical Properties of the Period 3 Elements, Periodicity of Chemical Properties of the Period 3 Elements and Predicting Properties, Group 2: Reactions of the Elements and Compounds, Thermal Decomposition and Solubility Trends, Group 17: Halogens, Hydrogen Halides, Halide Ions and the Reactions of Chlorine, Nitrogen and Sulfur: Ammonia, Oxides of Nitrogen and Atmospheric Pollution, Group 2: Explaining Trends in Thermal Stability and Solubility (A Level), Transition Elements: Electronic Configurations and General Properties (A Level), Transition Element Complexes: Ligands, Ligand Exchange and Redox Reactions (A Level), Color of Complexes (A Level), Stereoisomerism in Transition Element Complexes and Stability Constants (A Level)
- How to study for Unit 2 This page turns a particle-level comparison of two substances, a reagent-condition-observation-inference table, balanced redox half-equations with electron cancellation, a bracketed complex-ion formula with overall charge, a wavelength or absorbance graph tied to an energy change, a sequence of catalytic steps that sums to the overall reaction into one route: State the observation or trend, identify the particles being compared, and separate evidence from inference..
- The organizing decision Connect each periodic trend or test observation to the correct particles, balanced equation, and supported conclusion.
- What A Level adds Use oxidation state, ligand identity, coordination number, and overall charge to explain transition-metal observations and reactions. Topics: Group 2: Explaining Trends in Thermal Stability and Solubility; Transition Elements: Electronic Configurations and General Properties; Transition Element Complexes: Ligands, Ligand Exchange and Redox Reactions; Color of Complexes; Stereoisomerism in Transition Element Complexes and Stability Constants.
What Cambridge International AS & A Level Chemistry (9701) Unit 2 covers
Use this map to connect each assessed skill to the relationship or representation that makes it visible.
Periodicity of Physical Properties of the Period 3 Elements
periodicity; oxidation state; qualitative test02Periodicity of Chemical Properties of the Period 3 Elements and Predicting Properties
periodicity; oxidation state; qualitative test03Group 2: Reactions of the Elements and Compounds, Thermal Decomposition and Solubility Trends
periodicity; oxidation state; qualitative test04Group 17: Halogens, Hydrogen Halides, Halide Ions and the Reactions of Chlorine
periodicity; oxidation state; qualitative test05Nitrogen and Sulfur: Ammonia, Oxides of Nitrogen and Atmospheric Pollution
periodicity; oxidation state; qualitative test06Group 2: Explaining Trends in Thermal Stability and Solubility (A Level)
coordination number; ligand exchange; catalytic cycle07Transition Elements: Electronic Configurations and General Properties (A Level)
coordination number; ligand exchange; catalytic cycle08Transition Element Complexes: Ligands, Ligand Exchange and Redox Reactions (A Level)
coordination number; ligand exchange; catalytic cycle09Color of Complexes (A Level)
coordination number; ligand exchange; catalytic cycle10Stereoisomerism in Transition Element Complexes and Stability Constants (A Level)
coordination number; ligand exchange; catalytic cycleCambridge International does not publish a per-unit weighting for this exam.
Official unit name and weighting: Cambridge International syllabus.
Inorganic Chemistry
Connect the published share to the unit model
Inorganic Chemistry begins with particles and observations. Distinguishing an ion from an atom keeps charge, color, and reactivity attached to the correct species.
The syllabus publishes paper contributions rather than a percentage for this domain. These five pages organize periodicity, tests, redox evidence, and industrial conditions without claiming a fixed frequency.
Use the 3×3 map to pair each observation with an equation or particle-level cause. Check charge and electron transfer before drawing a conclusion. When a trend and a reaction appear together, keep their explanations separate before combining them.
Build an inorganic explanation in a fixed order: state the observed or predicted direction, identify the particles being compared, select the controlling principle, and connect cause to consequence. For periodic trends, separate nuclear charge, shielding, distance, bonding, and structure rather than treating position in the table as an explanation. For redox, write half-equations in one convention, balance electrons, and use the resulting direction to check the stated oxidising and reducing roles. For qualitative evidence, name the reagent and conditions, record the direct color, precipitate, gas, or solubility change, and make only the inference that the observation supports. A comparison earns its force by referring to both substances on the same property and closing with the requested conclusion.
Keep observation, equation, and explanation in separate lines until they agree. A visible color or state change is evidence; the named ion or oxidation state is an inference; the balanced equation is the conservation check. For a trend question, compare the same property for both substances, state the direction, and then explain how charge, radius, shielding, bonding, or intermolecular attraction changes the relevant energy. For an unfamiliar reaction, test atom balance, charge balance, electron transfer, and physical evidence before accepting the proposed products. This sequence prevents a remembered fact from being attached to the wrong species or comparison. Finish by matching the conclusion to the exact species and condition in the question.
The decision that organizes this unit
Define the system and choose the route before calculating
Connect each periodic trend or test observation to the correct particles, balanced equation, and supported conclusion.
State the observation or trend, identify the particles being compared, and separate evidence from inference.
Mechanism route and repair branches
Relationships to preserve
- Periodicity is shown through direction plus causal chain.
- Group chemistry is shown through reagent, condition, observation, inference.
- Redox is shown through half-equations and electron cancellation.
- Complexes is shown through ligands, charge, geometry.
- Color is shown through energy gap and wavelength.
- Catalysis is shown through steps sum to overall reaction.
Representations to read
- a particle-level comparison of two substances
- a reagent-condition-observation-inference table
- balanced redox half-equations with electron cancellation
- a bracketed complex-ion formula with overall charge
- a wavelength or absorbance graph tied to an energy change
- a sequence of catalytic steps that sums to the overall reaction
Branches to reject
- treating position in the periodic table as a complete explanation
- writing an ion identity as though it were a direct observation
- balancing atoms while leaving charge or electrons unbalanced
- confusing coordination number with oxidation state
- treating absorbed color as the observed color
- claiming catalysis without showing that the catalyst is regenerated
| Key concept | Why it's hard | What scores |
|---|---|---|
| Periodicity | Competing particle factors | Direction plus causal chain |
| Group chemistry | Observation versus identity | Reagent, condition, observation, inference |
| Redox | Atom balance can hide charge error | Half-equations and electron cancellation |
How Cambridge International AS & A Level Chemistry (9701) assesses Inorganic Chemistry (AS & A Level)
What a complete response must make visible
Match the task to evidence that a reader can audit, then check the most likely reasoning failure before finalizing the response.
| Task | Evidence to show | Hurdle |
|---|---|---|
| Periodicity of Physical Properties of the Period 3 Elements | periodicity; oxidation state; qualitative test | treating position in the periodic table as a complete explanation |
| Periodicity of Chemical Properties of the Period 3 Elements and Predicting Properties | periodicity; oxidation state; qualitative test | writing an ion identity as though it were a direct observation |
| Group 2: Reactions of the Elements and Compounds, Thermal Decomposition and Solubility Trends | periodicity; oxidation state; qualitative test | balancing atoms while leaving charge or electrons unbalanced |
| Group 17: Halogens, Hydrogen Halides, Halide Ions and the Reactions of Chlorine | periodicity; oxidation state; qualitative test | confusing coordination number with oxidation state |
| Nitrogen and Sulfur: Ammonia, Oxides of Nitrogen and Atmospheric Pollution | periodicity; oxidation state; qualitative test | treating absorbed color as the observed color |
| Group 2: Explaining Trends in Thermal Stability and Solubility (A Level) | coordination number; ligand exchange; catalytic cycle | claiming catalysis without showing that the catalyst is regenerated |
| Transition Elements: Electronic Configurations and General Properties (A Level) | coordination number; ligand exchange; catalytic cycle | treating position in the periodic table as a complete explanation |
| Transition Element Complexes: Ligands, Ligand Exchange and Redox Reactions (A Level) | coordination number; ligand exchange; catalytic cycle | writing an ion identity as though it were a direct observation |
| Color of Complexes (A Level) | coordination number; ligand exchange; catalytic cycle | balancing atoms while leaving charge or electrons unbalanced |
| Stereoisomerism in Transition Element Complexes and Stability Constants (A Level) | coordination number; ligand exchange; catalytic cycle | confusing coordination number with oxidation state |
Explain a Period 3 melting-point contrast
Read each question as it appears on the exam paper, choose your answer, then tap it to see the feedback.
Practice 1: Explain a Period 3 melting-point contrast
Sodium and magnesium are consecutive Period 3 elements.
Magnesium has a much higher melting point than sodium. Explain this difference without using numerical melting-point values.
[4]Refer to structure and bonding in your answer.
A. Magnesium is farther to the right in Period 3, so its melting point is higher.
❌ Not quite 😭 Position in the Period is a pattern, not a causal explanation. This does not compare the particles, delocalised electrons or strength of metallic attraction.
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B. Both have giant metallic lattices, but Mg²⁺ and two delocalised electrons per atom produce stronger attraction than Na⁺ and one electron, so more energy is needed.
✅ Correct! 😊 This compares like with like: structure, ion charge and electron contribution. It then links stronger electrostatic attraction to the greater energy required for melting.
C. Magnesium forms stronger covalent bonds than sodium and therefore has the higher melting point.
❌ Not quite 😭 The solids are described by metallic bonding, not discrete covalent bonds. Using the wrong bonding model prevents the explanation from addressing their giant metallic lattices.
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D. Magnesium has more protons, so its metallic bonding is stronger.
❌ Not quite 😭 More protons alone does not complete the comparison. The scoring chain needs Mg²⁺ versus Na⁺, two versus one delocalised electron, stronger attraction and the resulting energy difference.
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Full explanation
- Step 1State the common structure first: sodium and magnesium both form giant metallic lattices.
- Step 2Compare the metal ions: magnesium contributes Mg²⁺ ions, whereas sodium contributes Na⁺ ions.
- Step 3Compare electron contribution: each magnesium atom supplies two delocalised electrons, while each sodium atom supplies one.
- Step 4The stronger attraction in magnesium requires more energy to overcome, giving magnesium the higher melting point.
Practice 2: Interpret a complex-ion formula
The complex ion [Co(NH₃)₅Cl]²⁺ contains monodentate ligands.
Determine the oxidation state of cobalt, the coordination number of the complex ion and its most plausible geometry.
[3]Show how the overall charge is obtained.
A. Co oxidation state +2; coordination number 5; square pyramidal
❌ Not quite 😭 This treats the overall ion charge as the metal oxidation state and counts only the ammonia ligands. The coordinated chloride also donates one lone pair and has charge −1.
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B. Co oxidation state +3; coordination number 6; octahedral
✅ Correct! 😊 Five neutral NH₃ ligands and one Cl⁻ ligand give x − 1 = +2, so cobalt is +3. Six monodentate donors give coordination number 6 and an octahedral arrangement.
C. Co oxidation state +3; coordination number 5; tetrahedral
❌ Not quite 😭 The oxidation-state calculation is correct, but the donor count is not. Five ammonia molecules plus one chloride ion give six coordinate bonds, which does not support a tetrahedral geometry.
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D. Co oxidation state +1; coordination number 6; octahedral
❌ Not quite 😭 The coordination number and geometry agree with six donors, but the charge calculation is reversed. A −1 chloride ligand requires cobalt to be +3 for the complex to have charge +2.
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Full explanation
- Step 1Let the oxidation state of cobalt be x; NH₃ is neutral and coordinated Cl has charge −1.
- Step 2Use the overall charge: x + 5(0) − 1 = +2, giving x = +3.
- Step 3Five NH₃ ligands and one Cl⁻ ligand are six monodentate donors, so the coordination number is 6.
- Step 4A six-coordinate complex of this type has a plausible octahedral geometry.
Key terms for Unit 2: Inorganic Chemistry (AS & A Level)
Models, uses, and boundaries
- Redox Map
- Electron loss and gain connect oxidation state to balanced equations. Use this redox map when the question calls for the relationship described here.
- Metallic Bonding
- The electron counts support the relative attraction argument. Use this metallic bonding when the question calls for the relationship described here.
- Alvc-U2-A01
- The apparatus labels sample, heating, delivery, test paper, outlet, and result record. Use this alvc-u2-a01 when the question calls for the relationship described here.
- Displacement
- The net ionic equation displays two-electron transfer. Use this displacement when the question calls for the relationship described here.
- Equilibrium
- The activity ratio applies at a stated temperature. Use this equilibrium when the question calls for the relationship described here.
- Complex Map
- Wavelength reports an electronic energy difference. Use this complex map when the question calls for the relationship described here.
- Complex Charge
- Ligand and overall charges fix oxidation state. Use this complex charge when the question calls for the relationship described here.
- Alvc-U6-A01
- The path labels source, selector, blank, sample, detector, and readout. Use this alvc-u6-a01 when the question calls for the relationship described here.
- Ligand Exchange
- Incoming ligand and displaced water remain visible. Use this ligand exchange when the question calls for the relationship described here.
- Catalytic Cycle
- Summation cancels intermediates and catalyst. Use this catalytic cycle when the question calls for the relationship described here.
Cambridge International AS & A Level Chemistry (9701) Unit 2 FAQ
How much of Cambridge International AS & A Level Chemistry (9701) does Unit 2 carry?
Cambridge International does not publish a per-unit weighting for this exam.
What is the first move on a Inorganic Chemistry (AS & A Level) problem?
State the observation or trend, identify the particles being compared, and separate evidence from inference.
Which relationships should I preserve?
Periodicity is shown through direction plus causal chain. Group chemistry is shown through reagent, condition, observation, inference. Redox is shown through half-equations and electron cancellation. Complexes is shown through ligands, charge, geometry. Color is shown through energy gap and wavelength. Catalysis is shown through steps sum to overall reaction.
Which representations should I practice?
Practice moving among a particle-level comparison of two substances, a reagent-condition-observation-inference table, balanced redox half-equations with electron cancellation, a bracketed complex-ion formula with overall charge, a wavelength or absorbance graph tied to an energy change, a sequence of catalytic steps that sums to the overall reaction.
What error should I check before submitting an answer?
Check for treating position in the periodic table as a complete explanation; writing an ion identity as though it were a direct observation; balancing atoms while leaving charge or electrons unbalanced; confusing coordination number with oxidation state; treating absorbed color as the observed color; claiming catalysis without showing that the catalyst is regenerated.
Evidence workshop
Continue from the free model into complete practice
The full unit guide continues with the chapter’s worked examples, figures, scoring tables, and answer checks.
- Explain a Period 3 melting-point contrast
- Separate observation from inference in a gas test
- Audit halogen displacement with electrons
- Evaluate industrial conditions as a compromise
Full unit practice. Open the complete guide for the full evidence workshop and synthesis.
Related Cambridge International AS & A Level Chemistry (9701) unit guides
Cambridge International AS & A Level Chemistry (9701) Exam Guide & Review
The whole exam and its official unit sequence.01Physical Chemistry (AS & A Level)
Cambridge International does not publish a per-unit weighting for this exam.03Organic Chemistry (AS & A Level)
Cambridge International does not publish a per-unit weighting for this exam.04Analysis (AS & A Level)
Cambridge International does not publish a per-unit weighting for this exam.How to study Cambridge International AS & A Level Chemistry (9701) Unit 2
Start with the organizing decision
Before solving, restate the decision in operational terms: Connect each periodic trend or test observation to the correct particles, balanced equation, and supported conclusion.. Your first written move should be to State the observation or trend, identify the particles being compared, and separate evidence from inference..
Practice the same idea in several representations
Rotate through a particle-level comparison of two substances, a reagent-condition-observation-inference table, balanced redox half-equations with electron cancellation, a bracketed complex-ion formula with overall charge, a wavelength or absorbance graph tied to an energy change, a sequence of catalytic steps that sums to the overall reaction. Use each representation to practice Periodicity of Physical Properties of the Period 3 Elements, Periodicity of Chemical Properties of the Period 3 Elements and Predicting Properties, Group 2: Reactions of the Elements and Compounds, Thermal Decomposition and Solubility Trends, Group 17: Halogens, Hydrogen Halides, Halide Ions and the Reactions of Chlorine, Nitrogen and Sulfur: Ammonia, Oxides of Nitrogen and Atmospheric Pollution, Group 2: Explaining Trends in Thermal Stability and Solubility (A Level), Transition Elements: Electronic Configurations and General Properties (A Level), Transition Element Complexes: Ligands, Ligand Exchange and Redox Reactions (A Level), Color of Complexes (A Level), Stereoisomerism in Transition Element Complexes and Stability Constants (A Level), and explain what stays invariant when the surface form changes.
Turn each error into a repair check
After every attempt, audit the response for treating position in the periodic table as a complete explanation; writing an ion identity as though it were a direct observation; balancing atoms while leaving charge or electrons unbalanced; confusing coordination number with oxidation state; treating absorbed color as the observed color; claiming catalysis without showing that the catalyst is regenerated. Then redo only the first step that made the reasoning diverge, keeping units, direction, and model conditions visible.
Confirm current course details in the official Cambridge International syllabus for the 2025-2027 administration.
Where to go next
Return to the Cambridge International AS & A Level Chemistry (9701) to see every unit and plan your revision.