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At the beginning of 19th century organic compounds
were defined as
Compounds directly or indirectly obtained from plants
and animals are called as organic compounds
Compounds obtained from minerals are called as
inorganic compounds
A change in defination took place by synthesis of an
organic compound from an inorganic compound
WOHLER converted
Ammonium cyanate to Urea
(inorganic compd)
(org compd)
New defination
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Compounds containing covalently bonded carbon atom
or atoms are called as organic compounds
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Carbon is covalently bonded with hydrogen oxygen,
halogens, and sometimes with nitrogen and sulphur.
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Carbon atomic no 6 shows EC :s 2,4
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Valency = 4
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Similarly
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Nitrogen’s valency = 3
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Oxygen’s valency = 2
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Hydrogen valency = 1
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They have low melting and boiling points
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They are generally insoluble in water but soluble in
organic solvents
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They are poor conductors of heat and electricity
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Methane(CH4)
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In this compound one carbon atom is covalently bonded
to 4 hydrogen atoms
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C(2,4)
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Electron-dot cross
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structure
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Structural formula
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Molecular formula
H(1)
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Oxygen molecule(O2) contains 2 covalently bonded
oxygen molecule.
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O(2,6)
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Electron-dot cross
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structure
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Structural formula
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Molecular formula
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Nitrogen molecule(N2) contains 2 covalently bonded
nitrogen atoms
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N(2,5)
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Electron-dot cross
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Structure
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Structural formula
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Molecular formula
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Tetra valency
C(2,4) shows valency=4
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Multiple bonding
It can form carbon to carbon
Single bond
C-C
Double bond
C=C
Triple bond
C≡C
Catenation
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The property of direct bonding between atoms of same
element to form a chain is known as catenation.
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The remarkable property of carbon atom to form bonds
with itself and give rise to a single large struture or chain
is called catenation.
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The chain can be straight chain, branched chain or may
have network like structure
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Straight chain
struture
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Eg
branched chain
network like