This key facts covers Key Facts Summary within Alkenes for GCSE Chemistry. Revise Alkenes in Organic Chemistry for GCSE Chemistry with 20 exam-style questions and 15 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 9 of 14 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 9 of 14
Practice
20 questions
Recall
15 flashcards
📌 Key Facts Summary
- General formula: CₙH₂ₙ (2 fewer H than alkanes)
- Unsaturated = contains C=C double bond
- More reactive than alkanes (double bond can open)
- First four: Ethene (C₂H₄), Propene (C₃H₆), Butene (C₄H₈), Pentene (C₅H₁₀)
- Bromine water test: alkenes turn it colourless, alkanes don't
- Undergo addition reactions (atoms add across the double bond)
- Used to make polymers/plastics
- Made by cracking long-chain alkanes