An unsaturated compound has molecules in which one or more carbon‑carbon bonds are not single bonds.
Think of carbon bonds as roads: a single bond is a single lane, a double bond is two lanes, and a triple bond is three lanes. If a molecule has a double or triple lane, it’s unsaturated because it can still accept more atoms (like cars) without breaking the road.
Examples:
C₂H₄ with a double bond: \$C=C\$C₂H₂ with a triple bond: \$C\equiv C\$| Group | Symbol | Example |
|---|---|---|
| Alkane | C–C (single) | Methane, CH₄ |
| Alkene | C=C (double) | Ethene, C₂H₄ |
| Alkyne | C≡C (triple) | Acetylene, C₂H₂ |
| Alkyl | R– | Methyl CH₃– |
• Look for “C=C” or “C≡C” in the structure or formula – that’s your quick check for unsaturation.
• Remember the definition: “one or more carbon‑carbon bonds are not single bonds.”
• When you’re given a name, think of the suffix: -ene (double), -yne (triple).
• Practice drawing structures from names – the more you do, the faster you’ll spot the unsaturated bonds.