25-01-2013, 04:22 PM
CARBON AND ITS COMPOUNDS
[attachment=48511]
1) Occurrence of carbon :-
i) Carbon is found in the atmosphere, inside the earth’s crust and in
all living organisms.
ii) Carbon is present in fuels like wood, coal, charcoal, coke, petroleum,
natural gas, biogas, marsh gas etc.
iii) Carbon is present in compounds like carbonates,
hydrogen carbonates etc.
iv) Carbon is found in the free state as diamond, graphite, fullerenes etc.
2) Bonding in carbon – Covalent bond :-
The atomic number of carbon is 6, its electronic arrangement is 2,4, it has 4 valence electrons. It can attain stability by gaining 4 electrons, losing 4 electrons or sharing 4 electrons with other atoms.
It does not gain 4 electrons because it is difficult for the 6 protons to hold 10 electrons.
It does not lose 4 electrons because it needs a large amount of energy to lose 4 electrons.
So it shares 4 electrons with other atoms to attain stability resulting in the formation of covalent bonds.
Since carbon atom needs 4 electrons to attain stability, its valency is 4 and it is tetravalent.
3) Formation of covalent bonds :-
Covalent bond is chemical bond formed by the sharing of electrons
between atoms.
The sharing of one pair of electrons results in the formation of single
covalent bond, sharing of two pairs of electrons results in the formation
of double covalent bond and sharing of three pairs of electrons results
in the formation of triple covalent bond.
Eg :- Formation of single covalent bond in Hydrogen
molecule - H2
The atomic number of hydrogen is 1, its electronic arrangement is 1, it
has 1 valence electron. It needs 1 electron more to attain stability. So
two hydrogen atoms share 1 pair of electrons resulting in the formation
of a single covalent bond in hydrogen molecule H2.
[attachment=48511]
1) Occurrence of carbon :-
i) Carbon is found in the atmosphere, inside the earth’s crust and in
all living organisms.
ii) Carbon is present in fuels like wood, coal, charcoal, coke, petroleum,
natural gas, biogas, marsh gas etc.
iii) Carbon is present in compounds like carbonates,
hydrogen carbonates etc.
iv) Carbon is found in the free state as diamond, graphite, fullerenes etc.
2) Bonding in carbon – Covalent bond :-
The atomic number of carbon is 6, its electronic arrangement is 2,4, it has 4 valence electrons. It can attain stability by gaining 4 electrons, losing 4 electrons or sharing 4 electrons with other atoms.
It does not gain 4 electrons because it is difficult for the 6 protons to hold 10 electrons.
It does not lose 4 electrons because it needs a large amount of energy to lose 4 electrons.
So it shares 4 electrons with other atoms to attain stability resulting in the formation of covalent bonds.
Since carbon atom needs 4 electrons to attain stability, its valency is 4 and it is tetravalent.
3) Formation of covalent bonds :-
Covalent bond is chemical bond formed by the sharing of electrons
between atoms.
The sharing of one pair of electrons results in the formation of single
covalent bond, sharing of two pairs of electrons results in the formation
of double covalent bond and sharing of three pairs of electrons results
in the formation of triple covalent bond.
Eg :- Formation of single covalent bond in Hydrogen
molecule - H2
The atomic number of hydrogen is 1, its electronic arrangement is 1, it
has 1 valence electron. It needs 1 electron more to attain stability. So
two hydrogen atoms share 1 pair of electrons resulting in the formation
of a single covalent bond in hydrogen molecule H2.