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Although organic compounds are basically made up of carbon, hydrogen, oxygen and a few more elements, their number is far greater than the inorganic compounds which don't form bonds. At present almost five million organic compounds are known to
use Śmore than the elements of all the compounds put together!! The unique nature of carbon atom and the arrangement of the bond carbon forms with other atoms enable the existence of such a large number of organic compounds.
Due to its tetravalent nature carbon always form covalent bonds by sharing electrons with one, two, three or four carbon atoms or atoms of other elements or groups of atoms as discussed earlier.
The tetra covalency of carbon atom allows it to combine easily with other carbon atoms to form a stable chain like structure i.e., exhibiting the property of catenation. Catenation usually occurs because the atom-to-atom covalent bond is quite strong. The chains having different chain lengths and structures and combines with different elements it leads to the formation of a large number of compounds. Two unique features of carbon stand out due to this. They are:
The single bond formed between the carbon atoms is strong. This results in the formation of stable compounds. Carbon atom can also form stable bonds with other atoms like H, Cl, Br, O, etc.
Due to its small size the carbon atom can also form multiple bonds i.e., double and triple bonds with not only carbon but with atoms of other elements like oxygen, nitrogen, etc. The formation of these multiple bonds gives rise to a variety in the carbon compounds.
| Linked to four atoms with four single bonds.
Tetrahedral geometry (sp3 hybridisation)
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| Linked to three atoms with two single and one double bond.
Trigonal geometry (sp2 hybridisation)
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| Linked to two atoms with one single and one triple bond.
Linear geometry (sp hybridisation)
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What ever be the nature of bonding, all the compounds of carbon always have a total of four bonds around the carbon atom.
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