Overview
This lecture covers the importance, properties, structures, types, and reactions of carbon compounds, including their versatile nature, functional groups, homologous series, nomenclature, and some key examples.
Importance and Presence of Carbon Compounds
- Carbon compounds are found in daily items such as toothpaste, soap, medicines, paper, and food.
- Earth's crust has 0.02% carbon (as carbonates, hydrogen carbonates, coal, petroleum); atmosphere has 0.3% as COâ‚‚.
Differences Between Ionic and Carbon Compounds
- Carbon compounds are poor conductors of electricity; ionic compounds are good conductors.
- Carbon compounds have lower boiling and melting points than ionic compounds.
- Carbon compounds do not form ions; bonding is through covalent bonds, not ionic.
Covalent Bonding in Carbon Compounds
- Carbon's atomic number is 6; it has four valence electrons and forms covalent bonds by sharing electrons.
- Covalent bonds involve electron sharing between nonmetals (e.g., H₂—single bond, O₂—double bond, N₂—triple bond).
Versatile Nature of Carbon
- Catenation: Carbon atoms form long chains, branches, and rings by bonding with themselves.
- Saturated compounds have all single bonds; unsaturated have double or triple bonds.
- Carbon's small atomic size and strong bonds make its compounds stable and diverse.
Structures and Types of Carbon Compounds
- Saturated hydrocarbons (alkanes): Only single C-C bonds (e.g., ethane C₂H₆).
- Unsaturated hydrocarbons (alkenes, alkynes): Double or triple C-C bonds (e.g., ethene Câ‚‚Hâ‚„, ethyne Câ‚‚Hâ‚‚).
- Isomers: Compounds with same molecular formula but different structures (structural isomers).
- Cyclic compounds: Carbon rings (e.g., cyclohexane, benzene).
Functional Groups and Homologous Series
- Functional group: Atom/group replacing hydrogen in a hydrocarbon, giving compounds specific properties (e.g., -OH for alcohols).
- Homologous series: Series of compounds with same functional group, differing by CHâ‚‚ units, and similar chemical properties.
Nomenclature of Carbon Compounds
- Names based on number of carbons (prefix), bond type (suffix), and functional group.
- E.g., Meth- (1C), Eth- (2C), Prop- (3C), -ane (single bonds), -ene (double bonds), -yne (triple bonds), -ol (alcohol), -one (ketone).
Chemical Properties and Reactions
- Combustion: Carbon compounds burn in oxygen to give COâ‚‚, heat, and light.
- Oxidation: Alcohols oxidized to carboxylic acids using oxidizing agents.
- Addition: Hydrogen added to unsaturated fats to make saturated fats (hydrogenation).
- Substitution: Saturated hydrocarbons react with chlorine in sunlight to form substituted products.
Properties and Reactions of Ethanol and Ethanoic Acid
- Ethanol: Liquid, solvent, found in alcoholic drinks, used in medicines and as fuel additive.
- Ethanoic (acetic) acid: Weak acid, used in vinegar; forms esters with alcohols (esterification); reacts with bases and carbonates; forms soaps by saponification.
Soaps and Detergents
- Soaps: Sodium/potassium salts of long-chain carboxylic acids that clean oily dirt due to hydrophilic and hydrophobic ends.
- Soap molecules form micelles that trap and remove oily dirt when rinsed.
Key Terms & Definitions
- Catenation — Self-linking property of carbon atoms to form chains or rings.
- Saturated Compound — Carbon compound with only single bonds.
- Unsaturated Compound — Carbon compound with double or triple bonds.
- Functional Group — Atom or group replacing hydrogen in a hydrocarbon, imparting specific properties.
- Homologous Series — Series of compounds with same functional group and similar chemical properties.
- Isomers — Compounds with same molecular formula but different structures.
Action Items / Next Steps
- Draw structures of C₂H₆, C₂H₄, and C₂H₂ and identify if saturated/unsaturated.
- List examples of functional groups and the types of compounds they form (e.g., alcohols, ketones).
- Practice nomenclature: name compounds based on given structures.