Structural Characteristics
Composed solely of carbon and hydrogen; carbon atoms are linked in chains exclusively by carbon-carbon single bonds, with all remaining valencies satisfied by hydrogen atoms. They are classified as saturated acyclic hydrocarbons with the general formula CnH2n+2.
All carbon atoms are sp³ hybridized; the carbon skeleton adopts a three-dimensional zigzag conformation. The C-C bond length is 154 pm, the C-H bond length is approximately 110 pm, and the σ-bonds allow for free rotation.
Physical Property Characteristics
Physical state varies with the number of carbon atoms: C1–C4 are gaseous, C5–C16 are liquid, and those with more than 16 carbons are solid (note: neopentane, with 5 carbons, remains gaseous).
Melting and boiling points increase with the number of carbon atoms; among isomers, those with more branches exhibit lower melting and boiling points. Densities are lower than that of water (approximately 0.8 g/cm³); they are sparingly soluble in water but readily soluble in organic solvents.
