ICSE Class 10 Chemistry Chapter 12 Organic Chemistry

Chapter 12: Organic Chemistry

Important Points To Remember

1. Organic chemistry is a special branch of chemistry which deals with the study of compounds of Carbon other than Carbonates, Bicarbonates, Oxides of Carbon, Cyanides etc.

2. Earlier it was regarded that organic compounds can only be produced by nature under the influence of living force called vital force.

3. The vital force theory got the deathblow after the synthesis of Urea by Wohler by heating Ammoniumr cyanate.

4. Carbon atom has unique property to link with each other so as to form long chain or ring structure. This property is called catenation.

5. All organic compounds essentially contain carbon atom. Carbon has 4 valence electrons. Therefore to satisfy its valency carbon shares its electrons with other carbon atoms or with the atoms of other elements. As a result of sharing it leads to the formation of straight chain, branched chain, closed chain or the ring structures.

Straight chain: C-C-C-C

Branched chain: C-C-C with C attached to one of the middle carbons

Ring structure or Closed chain of carbon atoms: A hexagonal ring structure

6. The simplest organic compound is called hydrocarbon. These are the compounds of Hydrogen and Carbon only.

7. Hydrocarbon classification:

Hydrocarbon divides into: Aliphatic hydrocarbon or Open chain hydrocarbon, and Aromatic hydrocarbon or Closed chain hydrocarbon

Aliphatic hydrocarbon divides into: Saturated hydrocarbon or Paraffin or Alkane, and Unsaturated hydrocarbon

Unsaturated hydrocarbon divides into: Alkane and Alkyne

Teacher's Note

Understanding the structure of organic compounds helps us recognize why plastics, oils, and fuels have different properties - they're all just different arrangements of carbon and hydrogen atoms.

8. The characteristics of organic compounds are:

(i) All organic compounds are covalent in nature.

(ii) Almost all the organic compounds are insoluble in water but soluble in organic solvents like benzene, ether, carbon tetrachloride.

(iii) Organic compounds have relatively low melting point and boiling point.

(iv) All organic compounds are combustible in nature.

9. Differences between Organic compounds and Inorganic compounds.

Teacher's Note

When comparing sugar (organic) with salt (inorganic), we see why salt dissolves in water while oil doesn't - the difference in molecular structure determines solubility.

10. Earlier, the organic compounds were known by their common names. However, with the discovery of large number of organic compounds the proper scheme for the naming of the organic compounds was formulated by the International Union of Pure and Applied Chemistry. In short, this scheme is referred as IUPAC nomenclature.

11. The various guidelines given by IUPAC for the naming of organic compounds are:

(i) The chain having the maximum number of Carbon atoms is selected i.e. the number of carbon atoms present in one molecule of an organic compound.

(ii) The kind of covalent bonds present between the carbon atoms in the molecule.

For example:

C-C Single covalent bond

C=C Double covalent bond

C≡C Triple covalent bond

(iii) The spatial arrangement of carbon atoms i.e. straight chain or branched chain

C-C-C-C Straight chain

Branched chain with C attached to middle carbon

(iv) On the basis of the number of carbon atoms in one molecule the numbering is assigned from Greek language as shown in the table given below:

Teacher's Note

Learning the Greek prefixes for carbon chains is like learning the alphabet of organic chemistry - it unlocks the ability to name and understand thousands of different compounds.

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