Evaluation
Edexcel A-Level Chemistry 9CH0
Atomic Structure and the Periodic Table
Bonding and Structure
Inorganic Chemistry and the Periodic Table
Topic overviewFlame tests and how they workThermal decomposition of nitrates and carbonatesCarrying out flame tests and testing the gasesGroup 2 elements and their compoundsTrends in Group 7 and predicting fluorine and astatineHalogen displacement reactionsDisproportionation and the reactions of chlorineHalides with concentrated sulfuric acid, and the hydrogen halidesTesting for halide ions with silver nitrateTesting for carbonate and hydrogencarbonate ionsTesting for sulfate and ammonium ions
Formulae, Equations and Amounts of Substance
Topic overviewThe mole, molar mass and empirical formulaThe ideal gas equation and molar volumeEquations, concentration and reacting quantitiesStandard solutions, titration and uncertaintyPercentage yield, atom economy and acid reactionsCore practicals 1 to 3Empirical formula and water of crystallisation by experimentApparatus, uncertainty and mathematical skills
Organic Chemistry I
Topic overviewFormulae, homologous series and functional groupsIUPAC nomenclatureTypes of organic reaction and structural isomerismStereoisomerism and E/Z nomenclaturePractical techniques in organic chemistryAlkanes, crude oil and combustion pollutantsRadical substitutionAlkenes, the double bond and hydrogenationElectrophilic addition, Markovnikov's rule and the test for an alkeneAddition polymers and waste polymersNucleophilic substitution of halogenoalkanesRates of hydrolysis and the SN1 and SN2 mechanismsClassifying and oxidising alcoholsAlcohols: practical techniques and the core practicals
Modern Analytical Techniques I
Energetics I
Kinetics I
Equilibrium I
Acid-Base Equilibria
Energetics II
Redox II
Transition Metals
Topic overviewElectron configuration and what makes a transition metalComplex ions, ligands and the colour of transition metal ionsCoordination number, monodentate ligands and the shapes of complexesBidentate and multidentate ligands, and ligand exchangeVanadium and chromium chemistryReactions with sodium hydroxide and ammoniaCobalt and copper complexesLigand exchange, amphoteric behaviour and the chelate effectTransition metals as catalysts
Kinetics II
Organic Chemistry II
Topic overviewChiralityAldehydes, ketones and their oxidationReduction and nucleophilic addition of HCNTesting for a carbonyl group: 2,4-DNPH and the iodoform reactionCarboxylic acids and their reactionsEsters and acyl chloridesReflux, extraction and recrystallisationDistillation, melting temperature and working safely
Organic Chemistry III
Topic overviewThe structure of benzene and the evidence for itElectrophilic substitution of benzeneNitration, halogenation, Friedel-Crafts and phenolAmines: structure and basicityReactions of amines and preparing themAmides and condensation polymersAmino acids, zwitterions and proteinsEmpirical and molecular formulae from analytical dataGrignard reagents and multi-step synthesisPurification techniques and the aspirin preparation
Organic Chemistry III
The structure of benzene and the evidence for it
- 3 things to know
- Papers 2 and 3
Overview
Recall questions on the Kekulé structure and the delocalised model, and on the bond lengths, hydrogenation enthalpies and lack of reactivity that decide between them.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Why does benzene burn with a smoky flame?
Key term
How does the Kekulé model represent the structure of benzene?
Questions from this subtopic
Each one with the model answer underneath.
- 1
How does the Kekulé model represent the structure of benzene?
Model answer
As a hexagonal ring with alternating single and double carbon-carbon bonds.
- 2
In the delocalised model of benzene, what type of orbital does each carbon atom contribute to the π-system?
Model answer
Each carbon atom has one unhybridised p-orbital perpendicular to the ring plane.
- 3
How do the p-orbitals in benzene interact to form the delocalised system?
Model answer
Adjacent p-orbitals overlap sideways.
- 4
Describe the distribution of electrons in the delocalised model of benzene.
Model answer
Electrons are shared across all six carbon atoms, forming two ring-shaped electron clouds above and below the plane of the ring.
- 5
What enthalpy of hydrogenation would be predicted for cyclohexatriene based on the Kekulé structure?
Model answer
Approximately three times the enthalpy of hydrogenation of cyclohexene.
- 6
How does the actual enthalpy of hydrogenation of benzene compare to the predicted value for cyclohexatriene?
Model answer
Benzene releases significantly less energy than the predicted value for cyclohexatriene.
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