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Chemistry · Class 10 · Chapter 11: Organic Chemistry
8 min
Key points
- Organic chemistry is the branch of chemistry that deals with the study of compounds of carbon except carbonates, bicarbonates, carbides and carbon monoxide and carbon dioxide
- Carbon has atomic number 6 and electronic configuration 1s² 2s² 2p² with four valence electrons in outermost shell
- Carbon shows catenation property - the ability to form bonds with other carbon atoms to form chains and rings
- Carbon forms covalent bonds due to small size and shows tetravalency by forming four covalent bonds
- Hydrocarbons are compounds containing only carbon and hydrogen atoms
- Alkanes have general formula CnH2n+2, alkenes have CnH2n, and alkynes have CnH2n-2
- Saturated hydrocarbons contain only single bonds while unsaturated hydrocarbons contain double or triple bonds
- Functional groups are specific arrangements of atoms that give characteristic properties to organic compounds
- Homologous series is a group of compounds with same functional group and similar chemical properties
Definitions
- Organic Chemistry
- Organic chemistry is the branch of chemistry that deals with the study of compounds of carbon except carbonates, bicarbonates, carbides and carbon monoxide and carbon dioxide
- Catenation
- Catenation is the ability of carbon atoms to form bonds with other carbon atoms to form long chains and rings
- Hydrocarbons
- Hydrocarbons are organic compounds which contain only carbon and hydrogen atoms
- Functional Group
- A functional group is an atom or group of atoms that gives characteristic properties to an organic compound
- Homologous Series
- A homologous series is a group of compounds having the same functional group and similar chemical properties
Worked example
Define organic chemistry. Write three characteristics of organic compounds. Give the molecular formula of methane and ethane. (6 marks)
Organic chemistry is the branch of chemistry which deals with the study of carbon compounds. Three characteristics: (1) Organic compounds are covalently bonded (2) They have low melting and boiling points (3) They are mostly insoluble in water but soluble in organic solvents. Molecular formula of methane = CH₄, Molecular formula of ethane = C₂H₆
Common mistakes
- Students often include CO₂, CO, carbonates and bicarbonates as organic compounds
- Confusing the general formulas of alkanes (CnH2n+2), alkenes (CnH2n) and alkynes (CnH2n-2)
- Writing incorrect structural formulas without showing all four bonds of carbon
- Not memorizing the exact textbook definition of organic chemistry word-for-word
- Mixing up saturated and unsaturated hydrocarbons
Quick recap
Organic chemistry studies carbon compounds which are covalently bonded with low melting points. Hydrocarbons are classified as saturated (alkanes) and unsaturated (alkenes, alkynes). Homologous series have same functional group with successive CH₂ difference. Remember exact molecular formulas for first few alkanes.
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