ICSE Class 10 Answered
Nomenclature
It is the system of assigning names to organic compounds.
The Systems of Nomenclature is
- Trivial system
- IUPAC (International Union of Pure and Applied Chemistry) system
According to the Suffix IUPAC system, the name of an organic compound consists of three parts:
- Root word
- Prefix
- Root Word
It depends on the number of carbon atoms present in the longest carbon chain selected.
Number of carbon atoms |
Root word |
One carbon atom C1 |
Meth |
Two carbon atoms C2 |
Eth |
Three carbon atoms C3 |
Prop |
Four carbon atoms C4 |
But |
Five carbon atoms C5 |
Pent |
Six carbon atoms C6 |
Hex |
Seven carbon atoms C7 |
Hept |
Eight carbon atoms C8 |
Oct |
Nine carbon atoms C9 |
Non |
Ten carbon atoms C10 |
Dec |
Ø Suffix
The root word is followed by an appropriate suffix, which represents the nature of the bond in a carbon-carbon atom.
Nature of bond |
Suffix |
General name |
General formula |
Single bond (C–C) |
-ane |
Alkane |
CnH2n+2 |
Double bond (C=C) |
-ene |
Alkene |
CnH2n |
Triple bond (CΞC) |
-yne |
Alkyne |
CnH2n−2 |
Group (R-) |
-yl |
Alkyl |
CnH2n+1 |
Ø PrefixIt denotes the substituent, alkyl or functional group and its position in the carbon chain.
Di-, tri- and tetra- are used for two, three and four groups of the same type, respectively.
Functional Group:
Characteristics of a Functional Group
i. Compounds of the same functional groups are identified using the same type of tests.
ii. The physical and chemical properties of the compounds of different functional groups are different.
iii. There exists a homologous series of compounds containing a particular type of functional group.
Functional group |
General formulae |
Organic compound |
Suffix |
Examples with common and IUPAC name |
Halide –X (F, Cl, Br, I) |
R–X |
Haloalkanes |
ane |
CH3Cl Common name: Methyl chloride IUPAC name: Chloromethane |
Hydroxyl –OH |
R–OH |
Alcohols |
ol |
C2H5OH Common name: Ethyl alcohol IUPAC name: Ethanol |
Aldehyde –CHO |
R-HC=O |
Aldehydes |
al |
CH3CHO Common name: Acetaldehyde IUPAC name: Ethanal |
Carboxyl –COOH |
R-COOH
|
Carboxylic acids |
oic acid |
CH3CH2COOH Common name: Propionic acid IUPAC name: Propanoic acid |
Keto -COR |
R-CO-R |
Ketones |
one |
CH3COC2H5 Common name: Diethyl ketone IUPAC name: Pentanone |
Ethers -OR |
R–O–R′ |
Ethers |
oxy |
CH3–O–C2H5 Common name: Ethyl methyl ether IUPAC name: Methoxy ethane |