Organic names and reaction products: read the complete structure
Name and display the five required starting compounds, recognise the four suffixes and match product structures to the appropriate reaction.
Section C12.1 · Names of compounds
Cross-referenced from the related Cambridge IGCSE Chemistry 0620 or Physics 0625 teaching to the 0652 syllabus. Exact 0652 Core/Supplement objective coverage and this final-series course’s examiner fit still need specialist review. Written practice is self-checked and does not predict a Cambridge grade or demonstrate supervised laboratory competence.
Before you begin
- Read displayed formulas and ordinary carbon, oxygen and hydrogen bond counts.
- Recall the products of combustion, substitution, addition and ethanoic-acid reactions.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which name ending identifies the stated alcohol family?
What you will learn
- Name and draw methane, ethane, ethene, ethanol and ethanoic acid with every atom and bond.
- Recognise the required compound types and name/draw the corresponding reaction products while respecting tier boundaries.
The five starting compounds · 5 structures
Reaction product reference · match the reaction and your tier
Use the product names in the relevant reaction lesson. Chlorine monosubstitution, detailed alkene-addition products, oxidation and esterification are labelled Extended in their teaching sequences.
Write sodium ethanoate as CH₃COONa: Na⁺ plus one ethanoate ion. Write magnesium or calcium ethanoate as M(CH₃COO)₂: M²⁺ plus two ethanoate ions. These are ionic formula units, not a single neutral molecule with a covalent carbon–metal bond. The ion drawing shows the bonds within each ethanoate.
Read the name ending and then verify the structure
The required name endings identify alkanes (–ane), alkenes (–ene), alcohols (–ol) and carboxylic acids (–oic acid). The five Core starting compounds are methane CH₄, ethane CH₃CH₃, ethene CH₂=CH₂, ethanol CH₃CH₂OH and ethanoic acid CH₃COOH. A displayed formula must show each H separately along with every other atom and bond; grouped CH₃ notation is useful structural shorthand but is not a complete displayed drawing.
Verify the characteristic connection: alkanes are single-bonded hydrocarbons, alkenes have C=C, alcohols have the stated alcohol OH group, and carboxylic acids have COOH. A molecular formula gives atom totals, so use the stated alternatives or additional structure before claiming it always determines one unique family or molecule. C₂H₆O alone does not draw ethanol's C–O–H connections; CH₃CH₂OH does.
Match reaction products rather than memorising an unrelated list
Complete combustion products are carbon dioxide CO₂ and water H₂O. A suitable metal with ethanoic acid gives an ethanoate salt and hydrogen H₂; a base gives an ethanoate and water; a carbonate gives an ethanoate, carbon dioxide and water. The neutral-product drawings and ethanoate-ion drawing are in the expandable reference. Sodium ethanoate is CH₃COONa; magnesium and calcium ethanoates are Mg(CH₃COO)₂ and Ca(CH₃COO)₂, and copper(II) ethanoate is Cu(CH₃COO)₂. Ionic salts have formula units containing separate ions, not a made-up covalent carbon–metal bond.
When studying the corresponding Extended reactions, methane/chlorine monosubstitution gives chloromethane CH₃Cl and hydrogen chloride HCl; ethane similarly gives chloroethane CH₃CH₂Cl and HCl. Ethene addition gives 1,2-dibromoethane CH₂BrCH₂Br with bromine, ethane with hydrogen/Ni, or ethanol with steam/acid catalyst. Ethanol oxidation gives ethanoic acid, while the representative esterifications give methyl or ethyl ethanoate and water. Revisit the condition and structure together in each reaction lesson; these examples do not exhaust every possible longer-chain product.
Sources for this lesson
Pause and explain
Which description correctly identifies CH₃COOH?
Worked example
Name CH₃CH₂OH and CH₃COOH, identify their families, and describe how to draw each with every atom and bond.
Show the worked solution
- CH₃CH₂OH is ethanol, an alcohol; draw C–C–O–H, then three separate H on the first C and two on the second.
- CH₃COOH is ethanoic acid; draw the CH₃ carbon with its three separate H, linked to C(=O)–O–H.
- Ethanol totals C₂H₆O; ethanoic acid totals C₂H₄O₂. Each carbon has four bonds and each neutral oxygen two.
Answer Ethanol: alcohol, displayed C–C–O–H with all H, C₂H₆O. Ethanoic acid: carboxylic acid, displayed CH₃–C(=O)–O–H with each H separate, C₂H₄O₂.
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Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Name the five required starting compounds and sketch each with all atoms and bonds.
Give me a hint
Use the first expandable group, then compare atom and bond counts.
Compare my reasoning
- Methane CH₄ and ethane CH₃CH₃ are single-bonded hydrocarbons; ethene CH₂=CH₂ has the C=C double bond.
- Ethanol CH₃CH₂OH has an alcohol OH; ethanoic acid CH₃COOH has C(=O)–O–H.
- Expand every grouped H into its individual atom and bond, then check C four, neutral O two and H one.
Methane CH₄; ethane C₂H₆; ethene C₂H₄; ethanol C₂H₆O; ethanoic acid C₂H₄O₂, with every atom and bond shown as in the reference.
Look for these in your work
- All five names match their displayed drawings.
- Grouped hydrogens are expanded and ordinary valences checked.
Name and draw the neutral products of complete ethanol combustion; separately name and formulate the salt from ethanoic acid with calcium carbonate.
Give me a hint
A neutral molecular drawing and an ionic salt formula unit need different descriptions.
Compare my reasoning
- Complete ethanol combustion gives carbon dioxide, displayed O=C=O, and water, displayed H–O–H as schematic connectivity.
- Calcium carbonate gives calcium ethanoate Ca(CH₃COO)₂, plus CO₂ and H₂O.
- The calcium salt contains Ca²⁺ and two ethanoate ions; do not draw a covalent C–Ca bond.
Carbon dioxide O=C=O and water H–O–H; calcium ethanoate Ca(CH₃COO)₂ contains separate Ca²⁺ and two ethanoate ions.
Look for these in your work
- Neutral products are named and their bonds shown.
- The ionic salt's name, formula and ion ratio are correct.
A student labels CH₃CH₂OH an alkene because a molecular formula supposedly fixes the family, and joins Mg directly to carbon when drawing magnesium ethanoate. Correct the structure-based reasoning.
Give me a hint
Use actual connectivity for the first claim and separate ions for the second.
Compare my reasoning
- CH₃CH₂OH displays an alcohol OH and single C–C, so it is ethanol, an alcohol.
- Molecular totals alone do not always establish unique connectivity or family.
- Magnesium ethanoate Mg(CH₃COO)₂ contains Mg²⁺ plus two ethanoate ions, with covalent bonds within each ion rather than C–Mg.
CH₃CH₂OH is ethanol, an alcohol; Mg(CH₃COO)₂ is an ionic salt of Mg²⁺ and two ethanoate ions, without a covalent C–Mg bond.
Look for these in your work
- Family assignment uses the actual group.
- Ionic formula units and covalent molecular drawings are distinguished.
Common mistakes
- Calling grouped CH₃ notation fully displayed.
- Classifying ethanoic acid as a simple alcohol just because its COOH includes O–H.
- Treating every molecular formula as a unique connectivity description.
- Drawing an ionic metal ethanoate as a neutral covalent carbon–metal molecule.
What can you explain now?
Which family matches the name ending –oic acid and the COOH group?
Compare with the explanation
Carboxylic acids.
The group includes a carbonyl and O–H together; it differs from the simple alcohol group.
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Make it stick
Draw and name the five starting compounds, then choose one studied reaction and give its product names, structures or ionic formula units and the matching conditions.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.