Key term
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
Atomic Structure and the Periodic Table
Relative atomic mass and the mass spectrum
- 3 things to know
- Papers 1 and 3
Overview
Calculating relative atomic mass from isotopic masses and abundances, why the mass spectrum of a diatomic element shows several peaks, the isotope combinations behind the Cl₂ peaks at m/z 70, 72 and 74, the p² : 2pq : q² ratio of peak heights, and what the molecular ion peak shows.
What you need to know
Answer each one before you reveal it.
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Key term
If two isotopes have abundances p and q, what ratio describes the relative peak heights for a diatomic molecule?
Key term
What information does the molecular ion peak (M⁺) provide in a mass spectrum?
Questions from this subtopic
Each one with the model answer underneath.
- 1
How is Aᵣ worked out from mass spectrometry data?
Model answer
Aᵣ = Σ(isotopic mass × abundance) ÷ Σ(abundance)
- 2
Calculate the relative atomic mass when isotopic mass 1 = 63, abundance 1 = 69.2 %, isotopic mass 2 = 65, abundance 2 = 30.8 %.
Model answer
Relative atomic mass = (63 × 69.2 + 65 × 30.8) ÷ 100 = 63.6.
- 3
Why does the mass spectrum of a diatomic element show multiple peaks?
Model answer
Because peaks correspond to all possible combinations of isotopes in the molecule
- 4
In the mass spectrum of Cl₂, which isotope combination produces the peak at m/z 70?
Model answer
³⁵Cl–³⁵Cl
- 5
What isotope combination gives rise to the m/z 72 peak in the mass spectrum of Cl₂?
Model answer
³⁵Cl–³⁷Cl
- 6
Which isotope combination is responsible for the m/z 74 peak in the mass spectrum of chlorine gas?
Model answer
³⁷Cl–³⁷Cl
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