Organic ChemistryIntroduction

The Reactive Cousins

Part of AlkenesGCSE Chemistry

This introduction covers The Reactive Cousins 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 1 of 14 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 1 of 14

Practice

20 questions

Recall

15 flashcards

🛢️ The Reactive Cousins

If alkanes are the quiet, unreactive family members, then alkenes are their lively, energetic cousins! One little change — a double bond — transforms these molecules from sleepy saturated compounds into reactive powerhouses ready to grab onto anything that comes their way.
✋ The Spare Hand Analogy

Alkenes have a double bond — like having a spare hand ready to grab onto something! Alkanes use all their "hands" (bonds) holding hydrogens. Alkenes have two carbons sharing a double grip (C=C), so they can let go with one hand and grab something new. That's why they're so reactive — and perfect for making polymers!

The key difference is saturation. Alkanes are "saturated" — completely full of hydrogen atoms. Alkenes are "unsaturated" — they have a C=C double bond which can "open up" and add new atoms across it.

Without alkenes, we wouldn't have plastics, polymers, or many of the materials that make modern life possible. They're the building blocks that join together to make everything from plastic bottles to phone cases.

Keep building this topic

Read this section alongside the surrounding pages in Alkenes. That gives you the full topic sequence instead of a single isolated revision point.

Practice Questions for Alkenes

What is the general formula for alkenes?

  • A. CnH2n+2
  • B. CnH2n-2
  • C. CnH2n
  • D. CnH4
1 markfoundation

Explain what is meant by the term 'unsaturated' when applied to alkenes.

2 marksstandard

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

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