Alkenes

• As well as forming single bonds with other atoms , carbon atoms can form double bonds - This means that not all carbon atoms have to be linked to four other atoms as a double carbon-carbon bond can be present instead
• Hydrocarbons that have double bonds are unsaturated
• Alkenes have at least one double bond so are unsaturated
• What is the general formula for alkenes?

  CₙH₂ₙ
• What is the simplest alkene?

  Ethene
• Ethene , C₂H₄ , is made up of 2 carbon atoms and 4 hydrogen atoms and contains one double carbon-carbon bond
• Propene , C₃H₆ , is made up of 3 carbon atoms and 6 hydrogen atoms and contains one double carbon-carbon bond
• Butene , C₄H₈ , is made up of 4 carbon atoms and 8 hydrogen atoms and contains one double carbon-carbon bond
• Pentene , C₅H₁₀ , is made up of 5 carbon atoms and 10 hydrogen atoms and contains one double carbon-carbon bond
• Alkenes can be represented using displayed formulae
• Hydrocarbons that have double bonds are unsaturated and have the capacity to make further bonds - Alkenes are unsaturated hydrocarbons