Unit Overview
Hydrocarbons
CIE A-Level ChemistryΒ· 5 min read π n/a
1. Unit at a Glance
Hydrocarbons are the backbone of all organic molecules, from fossil fuels and plastics to biological compounds. This unit progresses from saturated alkanes (only single C-C bonds) to unsaturated alkenes (containing at least one C=C double bond), directly linking their bonding differences to differences in reactivity.
We build from basic structure and nomenclature to key reaction pathways and industrial applications. These fundamentals will be referenced constantly as you move to more complex organic compounds in subsequent units.
This unit covers the following core sub-topics:
2. Common Pitfalls
Wrong move:
Assuming alkanes are completely unreactive
Why:
Students often confuse low reactivity with polar reagents for no reactivity at all
Correct move:
Remember alkanes readily undergo combustion and radical substitution reactions under the right conditions
Wrong move:
Numbering alkene chains without prioritising the double bond position
Why:
Students often count the longest carbon chain but number from the wrong end, giving the double bond a higher locant than needed
Correct move:
Always number the parent chain to give the C=C double bond the lowest possible position number
3. Quick Reference Cheatsheet
Concept | Key Detail |
|---|---|
General formula (acyclic alkanes) | |
General formula (acyclic alkenes) | |
Typical reaction type (alkanes) | Radical substitution |
Typical reaction type (alkenes) | Electrophilic addition |
Ο bond strength vs Ο bond strength | Ο bonds are weaker than Ο bonds, making C=C more reactive |
What's Next
Begin this unit with the first sub-topic, Alkanes, to learn about the structure, properties and reactions of saturated hydrocarbons. After you complete both sub-topics in this unit, you will progress to the next unit covering halogen derivatives of hydrocarbons, which builds directly on the hydrocarbon reactivity fundamentals you will learn here.