Polymers and organic chemistry

Study H1 Chemistry organic structures and reactions, linking polymer and protein chemistry to material properties, recycling and sustainability.

GCE A-Level H1 Chemistry 2027
11 lessons

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Before you begin

Organic chemistry is the chemistry of carbon compounds, from fuels and medicines to plastics and proteins. This topic starts with how organic molecules are drawn and named, their isomers and shapes, and the reactions of the main classes of compound. It then uses those ideas to explain polymers: how they are made, why proteins fold and unfold, how a polymer’s structure decides its uses, and how plastics can be recycled.

Be comfortable with: O-Level organic chemistry, sigma and pi bonds, intermolecular forces, and balancing equations.

Learning goals

Name hydrocarbons (alkanes, alkenes and benzene) and use their general, structural and displayed formulae
Name halogenoalkanes and use their general, structural and displayed formulae
Name primary, secondary and tertiary alcohols and use their general, structural and displayed formulae
Name aldehydes and ketones and use their general, structural and displayed formulae
Name carboxylic acids and use their general, structural and displayed formulae
Name esters and use their general, structural and displayed formulae
Name amines and use their general, structural and displayed formulae
Name amides and use their general, structural and displayed formulae
Name amino acids and use their general, structural and displayed formulae
Interpret and use the term functional group
Interpret and use the terms addition, substitution and elimination
Interpret and use the terms condensation and hydrolysis
Interpret and use the terms oxidation and reduction for organic reactions
Describe structural (constitutional) isomerism, where isomers differ in how their atoms are connected
Describe cis–trans isomerism in alkenes and explain it by restricted rotation about the π bond
Deduce the possible isomers of a molecule from its molecular formula
Describe the shapes of ethane, ethene and benzene molecules
Explain the shapes and bond angles of ethane, ethene and benzene using their σ and π carbon–carbon bonds
Predict the shapes and bond angles of molecules similar to ethane, ethene and benzene
Describe alkanes, such as ethane, as unreactive apart from combustion and substitution by chlorine in ultraviolet light at room temperature
Describe the combustion of alkenes, such as ethene, and their addition reactions with bromine in CCl₄ and hydrogen over a nickel catalyst
Describe how halogenoalkanes, such as bromoethane, undergo substitution to alcohols with hot NaOH(aq) and elimination to alkenes with hot NaOH in ethanol
Describe the combustion of alcohols, such as ethanol, their oxidation to carboxylic acids with hot acidified K₂Cr₂O₇ or KMnO₄, and their elimination to alkenes with hot concentrated H₃PO₄
Describe the reduction of aldehydes and ketones to alcohols with LiAlH₄ or H₂ and nickel, and the oxidation of aldehydes to carboxylic acids with hot acidified K₂Cr₂O₇ or KMnO₄
Describe how carboxylic acids, such as ethanoic acid, form salts with alkalis and carbonates, esters with alcohols (concentrated H₂SO₄ catalyst) and amides with amines (using DCC)
Describe the hydrolysis of esters and amides, such as ethyl ethanoate and ethanamide, by heating with aqueous acid or alkali
Describe how amines, such as ethylamine, react with aqueous acid to form salts
Recognise polymers as macromolecules of monomers with an average relative molecular mass of at least 1000 or at least 100 repeat units
Classify polymers as addition or condensation polymers and explain the difference
Describe proteins as condensation polymers of α-amino acids joined by peptide (amide) bonds
Describe the hydrolysis of proteins by heating with aqueous acid or alkali
Describe how hydrogen bonds, intermolecular forces and ionic linkages hold a protein's three-dimensional structure
Explain how extremes of temperature and pH denature proteins by disrupting the bonds that hold their three-dimensional structure
Use protein structure changes to explain everyday effects, such as cooking egg white or adding vinegar to milk
Explain how thermoplastics such as poly(ethene) and thermosets such as poly(diallyl phthalate) differ in softening and recyclability, using structure and bonding
Explain how thermoplastics such as poly(ethene) and thermosets such as poly(diallyl phthalate) differ in rigidity, using structure and bonding
Explain how thermoplastics such as poly(ethene) and thermosets such as poly(diallyl phthalate) differ in strength, using structure and bonding
Explain why LDPE in plastic bags is softer and more flexible than HDPE in bottles, using structure and bonding
Explain why polyester (PET) fabric creases slightly less than polyamide (nylon 6,6), using structure and bonding
Explain why PVA dissolves in water for use in eye drops while PVC resists water for raincoats, using structure and bonding
Explain why strongly alkaline cleaners are stored in poly(propene) rather than PET containers, which they hydrolyse
Predict a polymer's physical properties from its structure
Recognise that poly(alkenes) are chemically inert and so hard to biodegrade
Recognise that polyesters and polyamides usually biodegrade by hydrolysis
Recognise that materials are finite and why recycling plastics matters, weighing economic, environmental and social factors

Syllabus statements covered

interpret, and use the nomenclature, general formulae and structural formulae (including displayed formulae) of the following classes of compounds: — hydrocarbons (alkanes, alkenes and benzene)
interpret, and use the nomenclature, general formulae and structural formulae (including displayed formulae) of the following classes of compounds: — halogenoalkanes
interpret, and use the nomenclature, general formulae and structural formulae (including displayed formulae) of the following classes of compounds: — alcohols (including primary, secondary and tertiary)
interpret, and use the nomenclature, general formulae and structural formulae (including displayed formulae) of the following classes of compounds: — aldehydes and ketones
interpret, and use the nomenclature, general formulae and structural formulae (including displayed formulae) of the following classes of compounds: — carboxylic acids
interpret, and use the nomenclature, general formulae and structural formulae (including displayed formulae) of the following classes of compounds: — esters
interpret, and use the nomenclature, general formulae and structural formulae (including displayed formulae) of the following classes of compounds: — amines
interpret, and use the nomenclature, general formulae and structural formulae (including displayed formulae) of the following classes of compounds: — amides
interpret, and use the nomenclature, general formulae and structural formulae (including displayed formulae) of the following classes of compounds: — amino acids
interpret, and use the following terminology associated with organic reactions: — functional group
interpret, and use the following terminology associated with organic reactions: — addition, substitution, elimination
interpret, and use the following terminology associated with organic reactions: — condensation, hydrolysis
interpret, and use the following terminology associated with organic reactions: — oxidation and reduction [in equations for organic redox reactions, the symbols [O] and [H] are acceptable]
describe constitutional (structural) isomerism
describe cis-trans isomerism in alkenes, and explain its origin in terms of restricted rotation due to the presence of π bonds [use of E, Z nomenclature is not required]
deduce the possible isomers for an organic molecule of known molecular formula
describe the shapes of the ethane, ethene and benzene molecules
explain the shapes of, and bond angles, in the ethane, ethene and benzene molecules in relation to σ and π carbon-carbon bonds [knowledge of hybridisation is not required]
predict the shapes of, and bond angles in, molecules analogous to those specified in (f)(ii)
describe the chemistry of the following classes of compounds: — alkanes (exemplified by ethane) as being generally unreactive except in terms of combustion and substitution by chlorine in the presence of ultraviolet light at room temperature
describe the chemistry of the following classes of compounds: — alkenes (exemplified by ethene) in terms of combustion and addition reactions with bromine (in CCl4) and hydrogen (using Ni catalyst)
describe the chemistry of the following classes of compounds: — halogenoalkanes (exemplified by bromoethane) in terms of substitution reaction to alcohols (using NaOH(aq), heat) and elimination reactions to alkenes (using NaOH in ethanol and heat)
describe the chemistry of the following classes of compounds: — alcohols (exemplified by ethanol) in terms of combustion, oxidation to carboxylic acids (using acidified K2Cr2O7 or acidified KMnO4 and heat) and elimination to alkenes (using concentrated H3PO4 catalyst and heat)
describe the chemistry of the following classes of compounds: — aldehydes (exemplified by ethanal) and ketones (exemplified by propanone) in terms of their reduction to primary and secondary alcohols respectively (using LiAlH4, or using H2(g), Ni catalyst) and oxidation of aldehydes to carboxylic acids (using acidified K2Cr2O7 or acidified KMnO4 and heat)
describe the chemistry of the following classes of compounds: — carboxylic acids (exemplified by ethanoic acid) in terms of: - reaction with alkalis and carbonates to form salts, - condensation with alcohols to form esters (in the presence of concentrated H2SO4 catalyst), and with amines (exemplified by ethylamine) to form amides (in the presence of dicyclohexylcarbodiimide, DCC) [knowledge of structure of DCC is not required]
describe the chemistry of the following classes of compounds: — esters (exemplified by ethyl ethanoate) and amides (exemplified by ethanamide) in terms of hydrolysis with aqueous acid (or aqueous alkali) and heat [detailed conditions involving specific temperature and pressure values are not required]
describe the chemistry of the following classes of compounds: — amines (exemplified by ethylamine) with aqueous acid to form salts
recognise polymers as macromolecules built up from monomers, with average relative molecular mass of at least 1000 or at least 100 repeat units
classify and explain the difference between addition and condensation polymers
describe proteins as examples of condensation polymers made up of α-amino acids as monomers, forming peptide (amide) bonds
describe the hydrolysis of proteins using aqueous acid (or aqueous alkali) and heat
describe the specific bonds or interactions that stabilise the three-dimensional structure of a protein: hydrogen bonding, intermolecular forces and ionic linkages [knowledge of the specific levels of structure of proteins, including a-helix and β-pleated sheet, is not required.]
explain denaturation of proteins by extremes of temperature and pH changes, in terms of disruption of the bonds or interactions that hold the three-dimensional structure of the proteins (see also LO 7(i))
apply knowledge of the loss and formation of three-dimensional structure to interpret real-world phenomena such as heating of egg whites and addition of vinegar to milk [candidates are not required to identify the proteins in the substances.]
classify and explain the difference between thermoplastic (linear, as exemplified by poly(ethene)) and thermosetting (cross-linked, as exemplified by poly(diallyl phthalate)) polymers with reference to structure, bonding and the following properties: — softening behaviour, including capacity to be recycled
classify and explain the difference between thermoplastic (linear, as exemplified by poly(ethene)) and thermosetting (cross-linked, as exemplified by poly(diallyl phthalate)) polymers with reference to structure, bonding and the following properties: — rigidity
classify and explain the difference between thermoplastic (linear, as exemplified by poly(ethene)) and thermosetting (cross-linked, as exemplified by poly(diallyl phthalate)) polymers with reference to structure, bonding and the following properties: — strength
describe and explain the types of structure and bonding in relation to the properties and uses as exemplified by the following: — low density poly(ethene) (LDPE) in plastic bag and high density poly(ethene) (HDPE) in plastic bottles in relation to LDPE being softer and more flexible, and HDPE being harder and stiffer
describe and explain the types of structure and bonding in relation to the properties and uses as exemplified by the following: — polyester and polyamide as fabric in relation to polyester (exemplified by poly(ethylene terephthalate) (PET)) as a fabric that is slightly less prone to creasing than polyamide (exemplified by nylon 6,6)
describe and explain the types of structure and bonding in relation to the properties and uses as exemplified by the following: — poly(vinyl alcohol) (PVA) as a water-soluble polymer in eye drops and poly(vinyl chloride) (PVC) as a water-resistant polymer used in raincoats
describe and explain the types of structure and bonding in relation to the properties and uses as exemplified by the following: — poly(propene) (PP) container instead of one made from poly(ethylene terephthalate) (PET) to store strongly alkaline cleaning solutions due to hydrolysis of PET
predict physical properties of polymer from its structure
recognise that poly(alkenes) are chemically inert and can therefore be difficult to biodegrade (see also 9(g)(i))
recognise that polyesters and polyamides are generally biodegradable by hydrolysis (see also 9(g)(vii))
recognise that materials are a finite resource and the importance of recycling plastics, considering the economic, environmental and social factors.

Lessons

Work through them in order.

Organic foundations and reactions

Macromolecules, proteins and materials

Practise and check

Or choose

Topic reference

Quick reference

Question	First move	What to show
Name a compound	find the main functional group and the longest chain containing it	ending, stem, side groups with position numbers
Cis–trans isomers?	find the C=C and list the groups on each carbon	each carbon must carry two different groups
Shape around a carbon	count the regions: 4 or 3	tetrahedral (109.5°) or trigonal planar (120°)
Predict a product	functional group → reagent → conditions	the product, and the type of reaction
Repeat unit of an addition polymer	open the C=C; keep the side groups in place	bonds through both brackets, and n
Monomers of a condensation polymer	break each ester or amide link	restore –OH, –COOH or -NH₂ at each end
Hydrolysis or denaturation?	are peptide bonds broken, or only the attractions holding the shape?	free amino acids show hydrolysis
Suitability of a polymer	branching, cross-links, polar groups or reactive links	structure → attractions → property → use

Core knowledge to remember

Isomers: compounds with the same molecular formula but different structures.
Cis–trans isomerism arises because there is no rotation about a C=C bond: rotation would break the π bond.
Alkenes undergo addition; halogenoalkanes undergo substitution with aqueous NaOH and elimination with NaOH in ethanol.
Primary alcohols and aldehydes are oxidised to carboxylic acids by acidified K₂Cr₂O₇ or KMnO₄; aldehydes and ketones are reduced to primary and secondary alcohols by LiAlH₄ or H₂/Ni.
Esters form from a carboxylic acid and an alcohol (concentrated H₂SO₄); amides form from a carboxylic acid and an amine (DCC). Both are hydrolysed by heating with aqueous acid or alkali.
Addition polymers form from alkenes with nothing given off; condensation polymers form from monomers with two functional groups, giving off a small molecule.
Denaturation is the loss of a protein’s three-dimensional shape when hydrogen bonds, intermolecular forces and ionic linkages are disrupted.
Thermoplastics soften on heating and can be recycled; thermosets are cross-linked and do not soften.

Common mistakes

Choosing a longest chain that does not contain the main functional group.
Assuming every alkene has cis–trans isomers.
Giving a reagent without its conditions, such as the solvent for NaOH.
Saying a ketone is oxidised to a carboxylic acid.
Giving the acid, not its salt, as a product of hydrolysis in alkali.
Leaving a C=C in the repeat unit of an addition polymer.
Saying denaturation breaks peptide bonds.
Naming the use of a polymer without explaining it from its structure.