Hydrocarbons Cheatsheet

Cheat Codes & Shortcuts

• Definition: Hydrocarbons are organic compounds composed solely of carbon and hydrogen atoms.
• Classification: Divided into Saturated (alkanes), Unsaturated (alkenes, alkynes), and Aromatic hydrocarbons.
• General Formula (Alkanes): \( C_nH_{2n+2} \)
• Alkene Formula: \( C_nH_{2n} \) — contain at least one double bond.
• Alkyne Formula: \( C_nH_{2n-2} \) — contain at least one triple bond.
• Aromatic Hydrocarbons: Have benzene rings with delocalized π-electrons.
• Isomerism: Structural isomers differ in connectivity; cis-trans isomers in alkenes differ in spatial arrangement.
• Naming: Follow IUPAC rules based on longest carbon chain and substituents.
• Combustion: Hydrocarbons combust in oxygen producing CO2 and H2O.
• Reaction Types: Substitution (alkanes), addition (alkenes/alkynes), and polymerization.

Quick Reference Table

Type	General Formula	Characteristic Reaction
Alkane (Saturated)	\( C_nH_{2n+2} \)	Substitution (e.g., combustion, halogenation)
Alkene (Unsaturated)	\( C_nH_{2n} \)	Addition (e.g., hydrogenation, halogenation)
Alkyne (Unsaturated)	\( C_nH_{2n-2} \)	Addition (e.g., hydrogenation, halogenation)
Aromatic	Benzene, \( C_6H_6 \)	Electrophilic substitution (e.g., nitration, sulfonation)

Advice

Hydrocarbons Quick Tips

• Alkanes: Generally unreactive but undergo substitution and combustion.
• Alkenes/Alkynes: More reactive; undergo addition reactions due to double/triple bonds.
• Aromatic Rings: Stability due to resonance; undergo electrophilic substitution.
• Isomerism: Remember cis-trans isomers occur only in alkenes with restricted rotation.
• Combustion: Complete combustion produces CO2 and H2O; incomplete leads to CO and soot.

Hydrocarbons Speed Quiz

Test your knowledge with 5 hydrocarbons questions! You have 30 seconds per question.