Cambridge International AS & A Level Chemistry Syllabus (9701) Comprehensive Notes

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Key Benefits of the Chemistry Syllabus

Motivating Interest: With over $50$ subjects, students can select those they love, which helps motivation.
Transferable Skills: Developing abilities valued by universities, including:
- Deep understanding of subjects.
- Higher-order thinking skills (analysis, critical thinking, problem-solving).
- Presenting ordered and coherent arguments.
- Independent learning and research.
- Handling data and applying the scientific method.
Student Attitudes: Development of concern for accuracy, precision, objectivity, integrity, enquiry, initiative, and inventiveness.
Cambridge Learner Attributes:
- Confident: Secure in knowledge and able to communicate through the language of science.
- Responsible: Developing safe scientific practices and working collaboratively.
- Reflective: Able to evaluate evidence to draw informed conclusions and recognizing science's impact on society/environment.
- Innovative: Applying skills to novel situations and new tools/IT.
- Engaged: Developing an enquiring mind for everyday life.

Key Concepts in Chemistry

Atoms and Forces: Matter is built from atoms interacting through electrostatic forces. Structure affects physical/chemical properties and reactivity.
Experiments and Evidence: Evidence from observation and experiments is used to build models and theories. Accuracy and reliability are central.
Patterns in Chemical Behaviour: Patterns are used to predict properties and design new substances or synthetic routes.
Chemical Bonds: Understanding bond making/breaking by electron movement predicts reactivity. Bond strength relates to material properties/uses.
Energy Changes: Energy changes predict the extent, feasibility, and rate of reactions.

Syllabus Overview and Aims

General Purpose: Enables students to acquire knowledge, apply scientific methods, develop data analysis skills, communicate science effectively, and care for the environment.
Neutrality: The syllabus is politically neutral and does not endorse any specific political view.
Subject Content Summary:
- AS Level (Topics 1–22): Atomic structure, stoichiometry, bonding, states of matter, chemical energetics, electrochemistry, equilibria, reaction kinetics, periodicity, Group 2, Group 17, Nitrogen/Sulfur, Organic Chemistry introduction, Hydrocarbons, Halogen compounds, Hydroxy compounds, Carbonyl compounds, Carboxylic acids, Nitrogen compounds, Polymerisation, Organic synthesis, Analysis (Infrared spectroscopy and Mass spectrometry), and practical skills.
- A Level (AS Topics + Topics 23–37): Advanced chemical energetics, advanced electrochemistry, advanced equilibria (acids/bases, partition coefficients), advanced kinetics, Group 2 trends, Transition elements, advanced Organic Chemistry (Arenes, Phenols, Acyl chlorides, Amides, Amino acids), Condensation polymerisation, advanced Organic synthesis, Analysis (Chromatography, Carbon-13 and Proton NMR).

Assessment Overview

Paper 1: Multiple Choice: $1\,hour\,15\,minutes$ . $40$ marks. $40$ four-choice questions based on AS content. Externally assessed. ( $31\%$ of AS, $15.5\%$ of A Level).
Paper 2: AS Level Structured Questions: $1\,hour\,15\,minutes$ . $60$ marks. Structured questions based on AS content. Externally assessed. ( $46\%$ of AS, $23\%$ of A Level).
Paper 3: Advanced Practical Skills: $2\,hours$ . $40$ marks. Practical work based on experimental skills in the syllabus. Externally assessed. ( $23\%$ of AS, $11.5\%$ of A Level).
Paper 4: A Level Structured Questions: $2\,hours$ . $100$ marks. Structured questions on A Level content (requires AS knowledge). Externally assessed. ( $38.5\%$ of A Level).
Paper 5: Planning, Analysis and Evaluation: $1\,hour\,15\,minutes$ . $30$ marks. Questions based on experimental skills of planning, analysis, and evaluation. Context may be outside the syllabus content. Externally assessed. ( $11.5\%$ of A Level).
Assessment Routes:
- Route 1 (AS Level only): Take Papers 1, 2, and 3 in the same series.
- Route 2 (Staged A Level): Year 1 take AS (Papers 1, 2, 3); Year 2 take A Level (Papers 4 and 5).
- Route 3 (Full A Level): Take Papers 1, 2, 3, 4, and 5 in the same series.

Assessment Objectives (AOs)

AO1: Knowledge and Understanding: Demonstrate knowledge of facts, laws, definitions, terminology, apparatus, applications (social/economic/environmental), and explanations of patterns.
AO2: Handling, Applying and Evaluating Information: Locate and select info; translate symbols/numerical data; identify patterns/trends; make predictions; evaluate hypotheses; solve problems.
AO3: Experimental Skills and Investigations: Plan experiments; collect/record observations; analyse/interpret data to reach conclusions; evaluate methods and quality of data.
Weightings:
- AO1 and AO2 are each $40\%$ of the total qualification.
- AO3 is $20\%$ of the total qualification.

Conventions and Nomenclature

Nomenclature: Follows Signs, Symbols and Systematics (ASE Companion, 2000). Traditional names like sulfite, nitrite, sulfur trioxide, sulfurous acid, and nitrous acid are used.
Spelling: Sulfur and its compounds are spelled with "f", not "ph".
Decimal Markers: A single dot on the line ( $.$ ).
Units: SI units or BIPM approved units (e.g., minute). Conversion to imperial units (inch, Fahrenheit) is not allowed.
Significant Figures: Failure to use appropriate significant figures, or misuse of units in ratios, may be penalized.

AS Level Physical Chemistry Details

Atomic Structure:
- Atoms are mostly empty space with a small dense nucleus ( $protons + neutrons$ ) and electrons in shells.
- Protons ( $Mass = 1, Charge = +1$ ); Neutrons ( $Mass = 1, Charge = 0$ ); Electrons ( $Mass = 1/1836, Charge = -1$ ).
- Atomic number ( $Z$ ) is proton count; Nucleon number ( $A$ ) is $protons + neutrons$ .
- Sub-shells: $s$ ( $1$ orbital, $2$ electrons), $p$ ( $3$ orbitals, $6$ electrons), $d$ ( $5$ orbitals, $10$ electrons).
- Shapes: $s$ (spherical), $p$ (dumb-bell shaped).
- Electronic configuration order: 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p.
- Ionisation Energy (IE): First IE is the energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous $1+$ ions.
Stoichiometry:
- Unified atomic mass unit ( $u$ ): $1/12^{th}$ mass of a carbon-12 atom.
- Avogadro constant ( $L$ ): $6.022 \times 10^{23}\,mol^{-1}$ .
- Empirical formula: Smallest whole-number ratio of atoms in a compound.
- Molecular formula: Actual number of atoms of each element in a molecule.
Chemical Bonding:
- Ionic: Electrostatic attraction between oppositely charged ions.
- Metallic: Electrostatic attraction between positive metal ions and delocalised electrons.
- Covalent: Electrostatic attraction between nuclei and a shared pair of electrons.
- VSEPR Theory shapes:
  - $BF_3$ : Trigonal planar ( $120^{\circ}$ ).
  - $CO_2$ : Linear ( $180^{\circ}$ ).
  - $CH_4$ : Tetrahedral ( $109.5^{\circ}$ ).
  - $NH_3$ : Pyramidal ( $107^{\circ}$ ).
  - $H_2O$ : Non-linear ( $104.5^{\circ}$ ).
  - $SF_6$ : Octahedral ( $90^{\circ}$ ).
  - $PF_5$ : Trigonal bipyramidal ( $120^{\circ}$ and $90^{\circ}$ ).
- Intermolecular Forces: include van der Waals' forces (id-id / London forces and pd-pd forces) and hydrogen bonding.
Chemical Energetics:
- Enthalpy change ( $\Delta H$ ): negative for exothermic, positive for endothermic.
- Standard conditions: $298\,K$ and $101\,kPa$ .
- $q = mc\Delta T$ ; $\Delta H = -\frac{mc\Delta T}{n}$ .
- Hess’s Law: Total enthalpy change is independent of the route taken.
Equilibria:
- Dynamic equilibrium: Rate of forward reaction equals rate of reverse reaction in a closed system.
- Le Chatelier’s Principle: System moves to minimise change.
- Acids/Bases: Brønsted–Lowry theory defines acids as proton donors and bases as proton acceptors.

A Level Physical Chemistry Details

Lattice Energy (\Delta H_{latt}): Enthalpy change when gaseous ions form one mole of a solid crystal lattice (always negative).
Born-Haber Cycles: Used to calculate lattice energy from atomisation, ionisation, electron affinity, and formation data.
Entropy (S): The number of possible arrangements of particles and energy in a system. $\Delta S^{\ominus} = \Sigma S^{\ominus}(products) - \Sigma S^{\ominus}(reactants)$ .
Gibbs Free Energy (\Delta G): Equation: $\Delta G^{\ominus} = \Delta H^{\ominus} - T\Delta S^{\ominus}$ . Reaction is feasible if $\Delta G \le 0$ .
Electrochemistry:
- Faraday Constant ( $F$ ): $9.65 \times 10^4\,C\,mol^{-1}$ . Relation: $F = Le$ .
- Nernst Equation: $E = E^{\ominus} + (\frac{0.059}{z})\log(\frac{[oxidised\,species]}{[reduced\,species]})$ .
- Gibbs and Potential: $\Delta G^{\ominus} = -nE^{\ominus}_{cell}F$ .

Inorganic Chemistry

Period 3 Trends: Periodicity in atomic radius, melting point, and electrical conductivity.
Oxides: $Na_2O, MgO, Al_2O_3$ (basic/amphoteric) vs $P_4O_{10}, SO_2, SO_3$ (acidic).
Group 2 (Mg to Ba):
- Reactivity increases down the group. Nitrates and carbonates become more thermally stable down the group because of lower polarizing power of larger cations.
- Solubility of hydroxides increases down the group; solubility of sulfates decreases.
Group 17 (Halogens):
- Volatility decreases down grouped ( $Cl_2\,(g), Br_2\,(l), I_2\,(s)$ ).
- Oxidising power: Cl_2 > Br_2 > I_2.
- Halide reducing power: I^- > Br^- > Cl^-.
Nitrogen and Sulfur: Nitrogen's lack of reactivity is due to the very strong triple bond ( $N \equiv N$ ). Oxides ( $NO_x$ ) contribute to acid rain and photochemical smog.
Transition Elements: Defined as d-block elements forming stable ions with incomplete d-orbitals.
- Properties: Variable oxidation states, catalytic behavior, complex ion formation, coloured compounds.
- Ligands: Monodentate ( $H_2O, NH_3, Cl^-, CN^-$ ), Bidentate (en, ethanedioate), Polydentate (EDTA).
- Crystal Field Splitting (\Delta E): Splitting of d-orbitals into two sets (Octahedral: $2$ high, $3$ low; Tetrahedral: $3$ high, $2$ low).

Organic Chemistry

Nomenclature Conventions: $R$ / $R'$ for alkyl groups; $X$ for halogens.
Mechanisms: Use of curly arrows to show electron pair movement is mandatory.
AS Level Compounds: Alkanes, Alkenes, Halogenoalkanes, Alcohols, Aldehydes, Ketones, Carboxylic acids, Esters, Amines (primary), Nitriles.
A Level Compounds: Arenes (Benzene), Halogenoarenes, Phenols, Acyl chlorides, Secondary/Tertiary amines, Amides, Amino acids.
Isomerism:
- Structural: Chain, positional, functional group.
- Stereoisomerism: Geometrical ( $cis/trans$ ) and Optical ( $enantiomers$ with chiral centres).
Reactions of Benzene: Electrophilic substitution (Nitration, Halogenation, Friedel-Crafts alkylation/acylation).
Nucleophilic Substitution: $S_N 1$ (via carbocation, tertiary) vs $S_N 2$ (one-step, primary).
Polymers:
- Addition: e.g., Poly(ethene), PVC.
- Condensation: Polyesters (diol + dicarboxylic acid) and Polyamides (diamine + dicarboxylic acid).
- Biodegradability: Polyesters and polyamides are biodegradable; poly(alkenes) are chemically inert.

Analytical Techniques (Data Section Values)

Infrared (IR): Characteristic ranges (e.g., $C=O$ amide $1640\u20131690\,cm^{-1}$ , $O-H$ alcohol $3200\u20133600\,cm^{-1}$ ).
Mass Spectrometry: $M+1$ peak formula for carbon count: $n = \frac{100 \times abundance\,of\,[M+1]^+}{1.1 \times abundance\,of\,M^+}$ .
Carbon-13 NMR: Shift ranges for $sp^3$ (alkyl $0\u201350\,ppm$ ) vs $sp^2$ (carbonyl $190\u2013220\,ppm$ ).
Proton (1H) NMR: Uses TMS as standard. Splitting follows the $n+1$ rule (singlet, doublet, triplet, quartet, multiplet).

Details of Practical Assessment (Paper 3 & 5)

Paper 3 Skills Breakdown:
- Manipulation, measurement, and observation: $12$ marks. Includes concordant titres (within $0.10\,cm^3$ ).
- Presentation of data: $6$ marks. Tables must have headings and units (e.g., $volume/cm^3$ ).
- Analysis, conclusions, and evaluation: $10$ marks. Identifying errors and suggesting improvements.
Uncertainty Calculation: Maximum uncertainty is half the smallest calibration.
- Example: Thermometer ( $1^{\circ}C$ gradations), uncertainty is $\pm 0.5^{\circ}C$ . For a temp change of $14.0^{\circ}C$ , percentage error = $\frac{2 \times 0.5}{14.0} \times 100 = 7.14\%$ .
Qualitative Analysis Notes Cations:
- $Al^{3+}$ : White ppt with $NaOH(aq)$ (soluble in excess), white ppt with $NH_3(aq)$ (insoluble in excess).
- $Cu^{2+}$ : Pale blue ppt with $NaOH(aq)$ (insoluble), pale blue ppt with $NH_3(aq)$ (soluble dark blue solution).
- $Fe^{2+}$ : Green ppt turning brown on contact with air (insoluble in excess).
- $Fe^{3+}$ : Red-brown ppt (insoluble in residue).
Qualitative Analysis Notes Anions:
- $CO_3^{2-}$ : $CO_2$ liberated by dilute acids.
- $Cl^-$ : White ppt with $Ag^+(aq)$ (soluble in $NH_3(aq)$ ).
- $SO_4^{2-}$ : White ppt with $Ba^{2+}(aq)$ (insoluble in strong acids).
Command Words:
- Analyse: Examine in detail.
- Deduce: Conclude from information.
- Define: Give precise meaning.
- State: Express in clear terms.
- Suggest: Apply knowledge to new situations.

Questions & Discussion

Previous Study Requirement: Recommended completion of Chemistry or Co-ordinated Science at IGCSE or O Level.
Guided Learning Hours: $180$ hours for AS Level; $360$ hours for full A Level.
Exam Series: Available in June and November; March for India only.
Retakes: Candidates can retake AS and A Level as many times as they want. AS results can be carried forward for A Level within set rules/time limits.
Language: Assessment available in English only.
Math Requirements: Logarithms (for pH), proportionality, gradients of tangents (for rates), and standard form ( $scientific\,notation$ ) are necessary skills.