Similar to the other first members of their respective groups, carbon is peculiar from the other members of the group. Carbon exhibits anomalous behavior because of the following properties:
Tetravalency of Carbon:
Carbon can hold only four pairs of electrons in its valence shell due to the availability of only s and p orbitals, it.
So, the covalence can be limited to four while other elements of the group have greater covalence because they have d-orbital.
Catenation is the property by which carbon forms long carbon chains with other carbon atoms.
Such a chain can contain a total of 70-80 carbon atoms.
This unique feature is responsible for the formation of very complex compounds having straight carbon chain, branched carbon chain and ring.
Small size of carbon:
Compounds formed by carbon are highly stable, because of its small size as the nucleus can effectively hold on to bonded and nonbonded electrons.
OCCURRENCE OF CARBON
The Earth’s crust contains only 0.02% carbon in the form of minerals (such as carbonates, coal, hydrogen carbonates).
About 0.03% carbon is present in the earth’s atmosphere in the form of carbon dioxide.
Organic chemistry deals with chemistry of compounds containing carbon and inorganic chemistry deals with chemistry of compounds not containing carbon. Organic chemistry is also chemistry of organic or living things.
Thus, all living or organic things contain carbon.
Carbon occurs in nature in two forms:
In the free state, carbon occurs in nature in two forms:
In the combined state, carbon occurs in nature in the form of compounds such as :
Carbon dioxide gas in air
Carbonates (like limestone, marble and chalk)
Fossil fuels like coal, petroleum and natural gas
Organic compounds like carbohydrates, fats and proteins, and