Saturated and unsaturated compounds

The idea

Carbon compounds with only single bonds between carbon atoms are saturated and normally not very reactive; those with double or triple bonds between carbon atoms are unsaturated and more reactive than saturated ones.

Single against double

Ethane has only single bonds between its carbon atoms. Ethene has a double bond between its two carbon atoms.

Which one do you expect to be more reactive?

• Ethane
• Ethene
• Both are equally reactive

Saturated or unsaturated?

Look at the bonds between the carbon atoms of each compound.

Look at the carbon-carbon bonds

Single bonds only means saturated. A double or triple bond means unsaturated, and the unsaturated compounds are more reactive.

Carbon compounds with only single bonds between carbon atoms are saturated and normally not very reactive. Those with double or triple bonds between carbon atoms are unsaturated and more reactive than saturated ones.

• Bonds between carbon atoms | Reactivity
• Saturated | only single bonds | normally not very reactive
• Unsaturated | double or triple bonds | more reactive

Notes

Compounds with only single bonds between carbon atoms are saturated and normally not very reactive. Those with double or triple bonds are unsaturated and more reactive.

Check yourself

Carbon compounds with only single bonds between the carbon atoms are called

Which compounds are more reactive?

Which of these is unsaturated?

What makes ethene, C₂H₄, unsaturated?

• Saturated compounds — correct. Yes!
• Unsaturated compounds. Unsaturated compounds have double or triple bonds between carbon atoms.
• Structural isomers. Structural isomers have identical molecular formulae but different structures. Compounds with only single bonds between carbon atoms are saturated.
• Saturated compounds. Saturated compounds are normally not very reactive.
• Unsaturated compounds — correct. Yes!
• They are equally reactive. Unsaturated compounds are more reactive than saturated compounds.
• Propane, C₃H₈. Propane has only single bonds between its carbon atoms, so it is saturated.
• Ethane, C₂H₆. Ethane has only a single bond between its carbon atoms, so it is saturated.
• Ethyne, C₂H₂, with a triple bond — correct. Yes!
• A double bond between its carbon atoms — correct. Yes!
• It has only four hydrogen atoms. Whether a compound is unsaturated depends on the bonds between its carbon atoms. Ethene is unsaturated because of its double bond.
• It has two carbon atoms. Ethane also has two carbon atoms and is saturated. It is the double bond that makes ethene unsaturated.