Chemistry study notes
Polymers and Organic Chemistry
Read organic structures, predict reactions and explain why a protein or plastic behaves as it does.
A-Level 8873, revised syllabus (2026-2027)
Choose a topic
12 topicsFormulae and names
A formula must show which atoms are joined, not just how many there are.
Organic isomers
Systematic drawing prevents repeated structures and missing isomers.
Molecular shapes
Describe the local geometry around a carbon before the whole molecule.
Hydrocarbon reactions
Follow the bond that changes and account for every product.
Halogenoalkanes and alcohols
Water favours substitution of bromoethane; ethanolic base promotes elimination.
Carbonyls, acids and amines
Carbonyl chemistry changes C=O; acid-base chemistry transfers protons.
Condensation and hydrolysis
The functional group and reaction medium determine the products.
Building polymer chains
Identify the repeat unit and the link formed between monomers.
Proteins and denaturation
Folding, denaturation and hydrolysis are different processes.
Chain packing and crosslinks
Explain a material property from its chain structure.
Choosing a polymer
Functional groups explain creasing, water response and chemical resistance.
Materials after use
Chemical resistance helps in service but can become a disposal problem.
Scope and references
Learning outcomes and sources
9. Polymers and Organic Chemistry (8873, 2026 revision; examinations 2026 and 2027). Use the outcome map to find the explanation for a particular syllabus requirement.
See the learning outcome map
9(a) Read and name the required organic families and formula representations.
- (i) Hydrocarbons: alkanes, alkenes and benzene.
- (ii) Halogenoalkanes.
- (iii) Alcohols including primary, secondary and tertiary.
- (iv) Aldehydes and ketones.
- (v) Carboxylic acids.
- (vi) Esters.
- (vii) Amines.
- (viii) Amides.
- (ix) Amino acids, including aminoethanoic acid.
- Nomenclature, general and structural/displayed formulae; empirical, molecular and skeletal representations from the preamble.
Read and name an organic structureLink oxidation level with acid-base behaviour
9(b) Use organic reaction terminology.
- (i) Functional group.
- (ii) Addition, substitution and elimination.
- (iii) Condensation and hydrolysis.
- (iv) Oxidation and reduction; [O] and [H] notation accepted.
Read and name an organic structureAn alkane substitutes; an alkene addsConditions choose the reaction routeLink oxidation level with acid-base behaviourMake and break ester or amide links
9(c) Describe constitutional isomerism.
- Same molecular formula; different connectivity.
9(d) Explain cis-trans isomerism in alkenes.
- Restricted rotation due to the pi bond; each C=C carbon must carry different substituents.
- E/Z nomenclature is not required.
9(e) Deduce isomers from a known molecular formula.
- Systematic skeleton and position changes; distinguish constitutional and cis-trans counts.
9(f) Explain organic molecular shapes through sigma and pi bonding.
- (i) Ethane, ethene and benzene shapes.
- (ii) Bond angles and sigma/pi carbon-carbon bonding; hybridisation is not required.
- (iii) Predict analogous shapes and angles.
9(g) Apply the specified organic reactions, conditions and analogous product predictions.
- (i) Ethane: general low reactivity, combustion, chlorine substitution under UV at room temperature.
- (ii) Ethene: combustion, Br2 in CCl4, H2/Ni addition.
- (iii) Bromoethane: aqueous NaOH/heat substitution; ethanolic NaOH/heat elimination.
- (iv) Ethanol: combustion; acidified K2Cr2O7 or KMnO4/heat oxidation to acid; concentrated H3PO4/heat elimination.
- (v) Ethanal and propanone reduction with LiAlH4 or H2/Ni; aldehyde oxidation with acidified K2Cr2O7 or KMnO4/heat.
- (vi) Ethanoic acid with alkalis and carbonates; alcohol ester formation with concentrated H2SO4; ethylamine amide formation with DCC (DCC structure not required).
- (vii) Ethyl ethanoate and ethanamide hydrolysis with aqueous acid or alkali and heat; correct protonation/salt products.
- (viii) Ethylamine with aqueous acid gives an ammonium salt.
- Preamble: essential reagents/conditions and major products; analogous product predictions; infer reasonable purification/extraction needs without detailed practical procedures.
An alkane substitutes; an alkene addsConditions choose the reaction routeLink oxidation level with acid-base behaviourMake and break ester or amide links
9(h) Recognise polymers as macromolecules built from monomers.
- Average relative molecular mass at least 1000 or at least 100 repeat units.
9(i) Distinguish addition and condensation polymers.
- Monomer functionality, bond formation, repeat units and presence or absence of small-molecule elimination.
9(j) Describe proteins as condensation polymers of alpha-amino acids.
- Peptide bonds are amide links; monomer groups and side chains remain correctly connected.
9(k) Describe protein hydrolysis.
- Aqueous acid or aqueous alkali and heat; peptide-bond cleavage and amino-acid-derived products.
9(l) Explain interactions stabilising three-dimensional protein structure.
- Hydrogen bonds, intermolecular forces and ionic linkages.
- Specific structural levels, alpha helices and beta pleated sheets are not required.
9(m) Explain protein denaturation.
- Temperature extremes and pH changes disrupt structure-stabilising interactions; link to enzyme behaviour in 7(i).
9(n) Apply protein shape changes to real phenomena.
- Heating egg white and adding vinegar to milk; loss and formation of three-dimensional arrangements.
- Names of the proteins are not required.
9(o) Compare thermoplastic and thermosetting polymers.
- Linear poly(ethene) and cross-linked poly(diallyl phthalate).
- (i) Softening and capacity for recycling.
- (ii) Rigidity.
- (iii) Strength; explain from structure and bonding.
9(p) Explain all named polymer structure-property-use comparisons.
- (i) LDPE bags: softer/flexible; HDPE bottles: harder/stiffer.
- (ii) PET polyester fabric slightly less prone to creasing than nylon 6,6 polyamide.
- (iii) PVA water-soluble in eye drops; PVC water-resistant in raincoats.
- (iv) PP rather than PET containers for strongly alkaline cleaner because PET hydrolyses.
Packing and crosslinks control how a plastic movesChoose the material for the job
9(q) Predict polymer physical properties from structure.
- Reason through branching, packing, crosslinks and available intermolecular interactions.
Packing and crosslinks control how a plastic movesChoose the material for the job
9(r) Relate polyalkene inertness to difficult biodegradation.
- Robust carbon backbone; connect to alkane reactivity in 9(g)(i).
9(s) Recognise hydrolysis as a biodegradation route for polyesters and polyamides.
- Ester and amide backbone cleavage; connect to 9(g)(vii); distinguish possible hydrolysis from its condition-dependent rate.
9(t) Evaluate recycling in the context of finite material resources.
- Economic, environmental and social factors.
- SEAB H1 Chemistry 8873, 2026 revision
Official scope: section 9, printed pages 19-22. All lettered outcomes and nested requirements checked.
- SEAB H1 Chemistry 8873, 2027
Section 9: same substantive outcomes as the revised 2026 course.
- NJC 8 Polymer Part 1 Student (Grail)
Consulted printed pp. 14-15 on chain, position and functional-group isomerism. Added an original systematic carbon-partition and hydrolysis-evidence example rather than a list of names.
- NJC 9 Polymer Part 2 (Grail)
Consulted and visually checked printed pp. 20-21 on neutral ester structures versus carboxylate hydrolysis products. Corrected charged ester-link notation. The source figure reverses two fragment-origin labels under ethyl ethanoate; our carbonyl/alcohol assignment was independently checked.