Why Alkenes Are More Reactive Than Alkanes

⚙️ 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.