Specification Point 4.23:
Know that Alkenes contain the function group C=C

Alkenes: A homologous series of hydrocarbon compounds with carbon-carbon double bonds (C = C)

Function Group of Alkenes

All alkenes will contain a double carbon bond, which is shown as two lines between two of the carbon atoms. The presence of this double bond allows alkenes to react in ways that alkanes cannot.

Example:

Alkenes function group, Edexcel IGCSE Chemistry
Specification Point 4.24:
Know the general formula for Alkenes

Alkenes General Formula

 n = number of carbon atoms                CnH2n

Specification Point 4.25:
Explain why alkenes are classified as unsaturated hydrocarbons

Classification of Alkenes

Alkenes: A homologous series of hydrocarbon compounds with double carbon bonds that has the general formula CnH2n

Alkenes are classified as unsaturated hydrocarbons as they contain a double covalent bond. See examples above.

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Author: Jamie

Jamie got a First class degree in Chemistry from Oxford University before going on to teach chemistry full time as a professional tutor. He’s put together these handy revision notes to match the Edexcel IGCSE Chemistry specification so you can learn exactly what you need to know for your exams.