- 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
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.
Practice questions for Alkenes
What is the general formula for alkenes?
Explain what is meant by the term 'unsaturated' when applied to alkenes.
Quick recall flashcards
What are alkenes?
Unsaturated hydrocarbons containing a C=C double bond
How are alkenes produced?
By cracking long-chain alkanes from crude oil