Exercise Solutions Available
Step-by-step answers for all textbook questions in this chapter
Quick Summary
Carbon forms millions of compounds due to its unique properties of catenation and tetravalency. This chapter covers the classification of organic compounds, hydrocarbons, functional groups, nomenclature, and isomers. Important for 3-mark and 5-mark questions.
Key Definitions
- Catenation: The ability of carbon atoms to bond with each other to form long chains.
- Tetravalency: Carbon's ability to form 4 covalent bonds.
- Organic Compounds: Compounds containing carbon (with hydrogen and other elements).
- Hydrocarbons: Compounds containing only carbon and hydrogen.
- Alkane: Saturated hydrocarbon with single bonds. General formula: CₙH₂ₙ₊₂.
- Alkene: Unsaturated hydrocarbon with one double bond. General formula: CₙH₂ₙ.
- Alkyne: Unsaturated hydrocarbon with one triple bond. General formula: CₙH₂ₙ₋₂.
- Functional Group: Group of atoms responsible for characteristic chemical properties.
- Isomers: Compounds with same molecular formula but different structural formulae.
Classification of Organic Compounds
Based on Carbon Chain
- Acyclic (open chain): Straight or branched chains.
- Cyclic (closed chain): Ring structures (alicyclic, aromatic).
Hydrocarbons
| Type | Bond | General Formula | Example |
|---|---|---|---|
| Alkane | Single (C–C) | CₙH₂ₙ₊₂ | CH₄ (methane), C₂H₆ (ethane) |
| Alkene | Double (C=C) | CₙH₂ₙ | C₂H₄ (ethylene) |
| Alkyne | Triple (C≡C) | CₙH₂ₙ₋₂ | C₂H₂ (acetylene) |
Common Functional Groups
| Functional Group | Class | Example |
|---|---|---|
| -OH | Alcohol | C₂H₅OH (ethanol) |
| -CHO | Aldehyde | HCHO (formaldehyde) |
| -CO- | Ketone | CH₃COCH₃ (acetone) |
| -COOH | Carboxylic acid | CH₃COOH (acetic acid) |
| -NH₂ | Amine | CH₃NH₂ (methylamine) |
| -X (F,Cl,Br,I) | Haloalkane | CH₃Cl (chloromethane) |
IUPAC Naming (Basic)
- Count the longest carbon chain → gives the parent name.
- Identify functional group → suffix (-ane for alkane, -anol for alcohol, -al for aldehyde, -oic acid for carboxylic acid).
- Number the chain from the end nearest to the functional group.
Isomers
- Compounds with same molecular formula but different structures.
- Example: C₄H₁₀ → butane (straight chain) and 2-methylpropane (branched).
- Properties (boiling point, reactivity) differ between isomers.
Important Questions
One Mark
- Define catenation.
- What is the general formula of alkanes?
- Name the functional group present in ethanol.
- What are isomers?
- Name the compound: CH₃COOH.
Short Answer (3 marks)
- Define catenation and tetravalency. How do these properties make carbon unique?
- Write the names and structures of the first three members of the alkane series.
- Distinguish between saturated and unsaturated hydrocarbons with examples.
Long Answer (5 marks)
- Explain the classification of organic compounds. Give examples for each class.
- What are functional groups? List five important functional groups with examples and the class of compounds they belong to.
Common Mistakes
- Confusing molecular formula with structural formula when defining isomers.
- Incorrect IUPAC naming — not numbering from the end nearest to the functional group.
- Forgetting that alkenes have double bonds and alkynes have triple bonds (not the other way around).
Revision Checklist
- [ ] Know catenation and tetravalency with examples
- [ ] Know general formulae for alkanes, alkenes, alkynes
- [ ] Know 5 common functional groups with class names
- [ ] Can write structural formulae for methane, ethane, ethylene, acetylene
- [ ] Understand what isomers are with one example
Frequently Asked Questions
Carbon is versatile because of two unique properties: Catenation (ability to form bonds with other carbon atoms, creating long chains, branches, and rings) and Tetravalency (carbon has 4 valence electrons and forms 4 bonds, allowing diverse compound formation).