CLASSIFICATION AND NOMENCLATURE
1. KEKULE’S PRINCIPLE
- Carbon has four valencies.
- Carbon has a property of catenation. It can make a large chain with addition of other carbons.
- A carbon atom can share 2, 4 or 6 electrons with other carbons & can form single, double or triple bond.
a carbon atom, it is not possible to make more than 3 bonds with
adjacent carbon atom because a carbon atom complete its octet from
overlapping which consists directional property.
2. THE FOUR VALENCIES OF CARBON ATOM CAN BE REPRESENTED BY FOLLOWING WAY
3. CLASSIFICATION OF CARBON
are four types of carbon present in organic compounds. The carbon which
is directly attached with one, two, three and four carbon atoms are
known as primary, secondary, tertiary and quarternary carbon atom
respectively. On the basis of carbon atom, hydrogen atoms bonded with
1º, 2º or 3º are named as primary, secondary or tertiary hydrogen atom
4. CLASSIFICATION OF ORGANIC COMPOUNDS:
IMPORTANT POINTS :
Saturated compounds having carbon-carbon single bonds.
e.g. CH4, CH3–CH3, CH3–CH2–CH3
Unsaturated compounds having atleast one carbon-carbon multiple bond (= or =)
compounds having similar types of atoms in the complete cycle. Whereas
heterocyclic compounds having atleast one different atom (O, S, N) in
Alicyclic = Aliphatic + homo/hetero cyclic
(Alipher = Fats)
compounds having sweet smell (aroma), cyclic resonance and follow
Huckle's rule (4n + 2 = p electrons) e.g. Benzenoid compounds :
5. HOMOLOGOUS SERIES
organic compounds which are structural ly similar having same
functional groups, combinedly gives a series known as homologous series
and the members as homologues.
The homologous series is characterised by :
(i) The two adjacent members are differ by a – CH2 – group or 14 atomic mass unit.
All the members of a series have same general formula, general methods
of preparation and similar chemical properties due to same functional
(iii) The homologues shows difference in physical
properties due to change in molecular mass and structural arrangement of
6. NOMENCLATURE OF ORGANIC COMPOUNDS
Mainly three system are adopted for naming of an organic compound :
(a) Common Name or Trivial Name System
(b) Derived Name System
(c) IUPAC Name or Jeneva Name System