CHAPTER :- 4TH
,• The earth’s crust has only 0.02% carbon in the form of minerals (like carbonates, hydrogen carbonates, coal and
petroleum) and the atmosphere has 0.03% of carbon dioxide
• It forms covalent compounds do not form ions because It could gain four electrons forming C4– anion. But it would be
difficult for the nucleus with six protons to hold on to ten electrons, that is, four extra electrons. It could lose four
electrons forming C4+ cation. But it would require a large amount of energy to remove four electrons leaving behind a
carbon cation with six protons in its nucleus holding on to just two electrons.
• The atomic number of carbon is 6.
• The bonds which are formed by the sharing of an electron pair between two atoms are known as covalent bonds.
Covalently bonded molecules are seen to have strong bonds within the molecule, but inter molecular forces are weak.
• Due to this the melting and boiling point of these compound is low
, Allotropes of carbon
The various physicals form of an element can exist are called allotropes
In diamond, each carbon atom is bonded to four other carbon atoms forming a rigid three-dimensional structure.
It is hardest natural substance it do not conduct electricity .
In graphite, each carbon atom is bonded to three other carbon atoms in the same plane giving a hexagonal array
chemical properties of both of them are the same
Diamonds can be synthesised by subjecting pure carbon to very high pressure and temperature.
Fullerenes form another class of carbon allotropes. The first one to be identified was C-60 which has carbon atoms
arranged in the shape of a football. Since this looked like the geodesic dome designed by the US architect Buckminster
Fuller, the molecule was named fullerene.
,• The earth’s crust has only 0.02% carbon in the form of minerals (like carbonates, hydrogen carbonates, coal and
petroleum) and the atmosphere has 0.03% of carbon dioxide
• It forms covalent compounds do not form ions because It could gain four electrons forming C4– anion. But it would be
difficult for the nucleus with six protons to hold on to ten electrons, that is, four extra electrons. It could lose four
electrons forming C4+ cation. But it would require a large amount of energy to remove four electrons leaving behind a
carbon cation with six protons in its nucleus holding on to just two electrons.
• The atomic number of carbon is 6.
• The bonds which are formed by the sharing of an electron pair between two atoms are known as covalent bonds.
Covalently bonded molecules are seen to have strong bonds within the molecule, but inter molecular forces are weak.
• Due to this the melting and boiling point of these compound is low
, Allotropes of carbon
The various physicals form of an element can exist are called allotropes
In diamond, each carbon atom is bonded to four other carbon atoms forming a rigid three-dimensional structure.
It is hardest natural substance it do not conduct electricity .
In graphite, each carbon atom is bonded to three other carbon atoms in the same plane giving a hexagonal array
chemical properties of both of them are the same
Diamonds can be synthesised by subjecting pure carbon to very high pressure and temperature.
Fullerenes form another class of carbon allotropes. The first one to be identified was C-60 which has carbon atoms
arranged in the shape of a football. Since this looked like the geodesic dome designed by the US architect Buckminster
Fuller, the molecule was named fullerene.
