An alkene is one of the four main types of hydrocarbons. Alkenes must contain at least one carbon to carbon double bond in their chain. Alkenes are true hydrocarbons, meaning they are made up of only hydrogen and carbon.
Alkenes have the molecular formula Cn H2n, where:
Alkenes are similar to Alkanes except they contain a double bond between two carbon atoms. When one carbon shares a double bond with another, this limits the number of hydrogen which can be bonded (resulting in less hydrogen atoms per carbon atom).
When there are 4 or more carbons in a chain, the position of the double bond can create different possible structures and uses a more precise nomenclature. Compounds that have the same chemical formula but have different bonding arrangements are called structural isomers
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