Final answer:
Saturated hydrocarbons (alkanes) like butane (C4H10) have only single bonds, while unsaturated hydrocarbons such as butene (alkenes, C4H8) have double bonds and butyne (alkynes, C4H6) have triple bonds. Hydrocarbons' saturation levels are determined by the presence and number of double or triple carbon-to-carbon bonds.
Step-by-step explanation:
The student is asking about the structural differences between saturated and unsaturated hydrocarbons, specifically for a four-carbon hydrocarbon skeleton.
Saturated hydrocarbons, or alkanes, follow the general formula CnH₂n+2, which means for a four-carbon alkane (C₄H₁₀), the structure would be butane with all carbon-to-carbon single bonds. This would require filling in the hydrogen atoms so that each carbon atom has four bonds, resulting in H₃C-CH₂-CH₂-CH₃.
For unsaturated hydrocarbons, we can consider alkenes and alkynes. Alkenes have at least one double bond (C=C) and follow the formula CnH₂n, which for a four-carbon alkene would be C₄H₈, such as butene. Alkynes have at least one triple bond (C≡C) and follow the formula CnH₂n-2, so a four-carbon alkyne would be C₄H₆, such as butyne. In both cases, the hydrocarbons have fewer hydrogen atoms than alkanes because of the presence of double or triple bonds.
To clarify, for C₄H₈, the student could depict but-1-ene as CH₂=CH-CH₂-CH₃, and for C₄H₆, the student could depict but-1-yne as HC≡C-CH₂-CH₃.