Simply CBSE

Carbon and Its Compounds β€” Class 10 Science

Quick revision notes for exam preparation.

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πŸ“Œ Key Points

  • Carbon valency: Always 4. Forms 4 covalent bonds (single, double, or triple)
  • Catenation: Ability of carbon to bond with itself, forming long stable chains and rings
  • Hydrocarbons: Compounds containing only C and H atoms. Classified by bond type
  • Alkanes: Cβ‚™Hβ‚‚β‚™β‚Šβ‚‚, single bonds only, saturated, less reactive, general formula Cβ‚™Hβ‚‚β‚™β‚Šβ‚‚
  • Alkenes: Cβ‚™Hβ‚‚β‚™, contain C=C double bond, unsaturated, more reactive, undergo addition
  • Alkynes: Cβ‚™Hβ‚‚β‚™β‚‹β‚‚, contain C≑C triple bond, highly unsaturated and reactive
  • Saturated compounds: Only single bonds, less reactive, higher melting/boiling points
  • Unsaturated compounds: Double or triple bonds, more reactive, can undergo addition reactions
  • Functional groups: -OH (alcohol), -CHO (aldehyde), -COOH (carboxylic acid), -CO- (ketone)
  • Isomers: Same molecular formula, different structural arrangements, different properties
  • Combustion: Cβ‚™Hβ‚‚β‚˜ + Oβ‚‚ β†’ COβ‚‚ + Hβ‚‚O + Heat (complete) or CO + C + Hβ‚‚O (incomplete)
  • Complete combustion: Blue flame, produces COβ‚‚ + Hβ‚‚O, maximum energy released
  • Incomplete combustion: Yellow flame, produces CO + soot + Hβ‚‚O, less energy, toxic CO
  • Diamond: 3D tetrahedral network, hardest, transparent, non-conductor
  • Graphite: Layered structure, soft, black, conducts electricity, free Ο€-electrons
  • Allotropes of carbon: Same element, different structures (diamond, graphite, fullerenes) = different properties
  • Boiling point trend: Increases with chain length (~20K per CHβ‚‚) due to van der Waals forces
  • IUPAC nomenclature: Prefix (C number) + Root (bond type) + Suffix (functional group)
  • C-C bond length: Single (154 pm) > Double (134 pm) > Triple (120 pm)
  • Structural isomerism: Different arrangement of atoms. Positional isomerism: Functional group at different position

πŸ“˜ Important Definitions

Hydrocarbon
A compound containing only carbon and hydrogen atoms. Classified as alkanes (single bonds), alkenes (double bonds), or alkynes (triple bonds).
Catenation
The ability of carbon atoms to form strong C-C bonds with each other, creating long chains and complex structures.
Functional Group
Specific atom or group of atoms bonded in particular way that determines compound's chemical properties. Examples: -OH, -CHO, -COOH.
Isomers
Compounds with same molecular formula but different structural arrangements, resulting in different physical and chemical properties.
Saturated Compound
Organic compound with only single C-C bonds. All bonding positions filled. Less reactive. Examples: Alkanes.
Unsaturated Compound
Organic compound with C=C or C≑C multiple bonds. More reactive, can undergo addition reactions. Examples: Alkenes, alkynes.
Allotropes
Different forms of same element in same physical state. Carbon allotropes: Diamond (hard, 3D network), Graphite (soft, layered), Fullerenes (cage-like).
Combustion
Burning of substance in oxygen releasing heat and light. Complete: Cβ‚™Hβ‚‚β‚˜ β†’ COβ‚‚ + Hβ‚‚O. Incomplete: Limited Oβ‚‚ β†’ CO + C + Hβ‚‚O.
Homologous Series
Group of compounds with same functional group, differing by CHβ‚‚ units, showing gradual change in properties.
van der Waals Forces
Weak intermolecular forces between molecules. Increase with chain length, explaining boiling point trend in alkanes.

⚠️ Common Mistakes

βœ— Wrong: Carbon has variable valency like other elements.

βœ“ Correct: Carbon valency is ALWAYS 4. It forms different types of bonds (single, double, triple) but always totaling 4 bonds.

βœ— Wrong: Saturated compounds are 'full of bonds' so they are most stable.

βœ“ Correct: Saturated means SINGLE BONDS ONLY. Unsaturated (double/triple bonds) are MORE reactive because multiple bonds can break and add other atoms.

βœ— Wrong: All isomers have the same properties.

βœ“ Correct: Isomers have SAME molecular formula but DIFFERENT structures and DIFFERENT properties (boiling point, reactivity, etc.).

βœ— Wrong: Diamond is soft and graphite is hard because of different elements.

βœ“ Correct: Both are carbon allotropes! Diamond is HARD (3D network), graphite is SOFT (layered). Structure determines property, not composition.

βœ— Wrong: Complete combustion produces CO and water.

βœ“ Correct: Complete combustion (sufficient Oβ‚‚) produces COβ‚‚ and Hβ‚‚O. CO is produced only in INCOMPLETE combustion (limited Oβ‚‚).

βœ— Wrong: Functional groups don't affect compound properties much.

βœ“ Correct: Functional groups DETERMINE properties! Same carbon skeleton with different functional groups = completely different compounds with different properties.

πŸ“ Exam Focus

These questions are frequently asked in CBSE exams:

Write equations for combustion of alkanes/alkenes and explain complete vs incomplete combustion.
5m
Compare properties of diamond, graphite, and fullerenes. Explain why same element has different properties.
5m
Define isomerism. Give examples of structural isomers and positional isomers with properties.
3m
Explain why carbon forms millions of compounds. Discuss catenation and bonding diversity.
5m
Write IUPAC names for given hydrocarbons and functional groups.
1m
Classify hydrocarbons - alkanes, alkenes, alkynes. Give general formulas and examples.
3m
Explain boiling point trend in alkane series. Why does it increase with chain length?
3m
Describe role of functional groups in determining compound properties. Give examples.
3m

🎯 Last-Minute Recall

Close your eyes and try to recall: Key definitions, formulas, and 3 common mistakes. If you can recall 80% without looking, you're exam-ready!