This how it works covers Why Alkenes Are More Reactive Than Alkanes 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 4 of 14 in this topic. Use this how it works to connect the idea to the wider topic before moving on to questions and flashcards.
⚙️ Why Alkenes Are More Reactive Than Alkanes
The C=C double bond is the source of alkene reactivity. The double bond (C=C) means two pairs of electrons are shared between the carbon atoms. One of these pairs is easier to break and provides the reaction site.
How addition reactions work:
- A small molecule (H₂, Br₂, H₂O) approaches the C=C double bond
- One bond of the double bond opens up
- Each atom from the added molecule bonds to one of the two carbons
- The result is a single bond between those carbons — a saturated product
- This is why the reaction is called an addition reaction — atoms are added across the double bond
Why alkanes don't do this: Alkanes only have single C-C bonds, which are much stronger and require significant energy (or UV light) to break. There is no reactive double bond available. This is why alkenes are useful for making polymers — their double bonds can react — while alkanes are mainly used as fuels.
Practice questions for Alkenes
What is the general formula for alkenes?
Explain what is meant by the term 'unsaturated' when applied to alkenes.