Saturated
No C=C or C≡C bond is present.
Each carbon reaches four sigma-bond connections when implicit C–H bonds are counted.
Molecular compound · alkane
Propane
C₃H₈
Propane is C₃H₈, the three-carbon alkane CH₃–CH₂–CH₃. All carbon–carbon bonding is single-bond sigma bonding, so the molecule is saturated and can rotate around its C–C bonds.
Fuel distinction: LPG and bottled fuel products are mixtures that can contain propane and butane. Propane itself is one defined compound.
Essentials
Three carbons joined only by single bonds define propane as an alkane.
The condensed formula CH₃–CH₂–CH₃ shows a saturated three-carbon chain.
Detail
The 2D structure is only one projection of a flexible molecule.
Each carbon is locally tetrahedral, and rotation about C–C single bonds generates different conformations without breaking connectivity.
Conformations
Rotation changes shape, not chemical identity.
A molecule can explore many conformations while remaining propane.
Understand
Complete combustion reorganizes propane into CO₂ and H₂O.
The balanced equation conserves three carbon atoms, eight hydrogen atoms and ten oxygen atoms across reactants and products.
Fuel chemistry
Combustion is not a single collision.
The balanced equation hides a network of bond-breaking, radical and oxidation steps.
Reference identifiers
Names and identifiers that pin down the chemical identity.
| Formula | C₃H₈ / CH₃CH₂CH₃ |
|---|---|
| CAS Registry Number | 74-98-6 |
| PubChem CID | 6334 |
Advanced
Push past the first model without losing the simple picture.
Why does propane rotate about C–C bonds?
A sigma bond is approximately cylindrically symmetric around the bond axis, so rotation does not destroy a π overlap.
Is propane planar?
No single rigid plane defines the whole molecule; its tetrahedral carbons and bond rotations give three-dimensional conformations.
Is LPG pure propane?
Not necessarily. Liquefied petroleum gas can contain propane, butane and other components.
Constituent elements