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CARBON AND ITS COMPOUNDS. CARBON. Carbon belongs to the group IV of the periodic table. It has four electrons in its outermost orbit, so its valency is four. Carbon is a non-metal. Compounds of Carbon are Widely Distributed in Nature.
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CARBON • Carbon belongs to the group IV of the periodic table. • It has four electrons in its outermost orbit, so its valency is four. • Carbon is a non-metal.
Compounds of Carbon are Widely Distributed in Nature • The number of carbon compounds is larger than that of all other elements put together.
Why so many Carbon Compounds in nature? • Because carbon is chemically unique. • Only carbon atoms have the ability to combine with themselves to form long chains
Carbon- Long Chains • A long chain, in turn, provides a convenient backbone of atoms to which other atoms can attach themselves in a variety of ways
Allotropes of Carbon • In nature, pure carbon occur in two forms- • Diamond • Graphite
What are Allotropes ? • Allotropes are elements which are chemically identical, but they differ markedly in their physical properties. • Diamond and Graphite – two allotropes of carbon differ in their physical properties.
How Diamond and Graphite are chemically identical? • These results of thes experiments answer this question: • On heating diamond or graphite in the air, they burn completely to form carbon dioxide. • Equal quantities of diamond and graphite when burned, produce exactly the same amount of carbon dioxide.
Why the physical properties of diamond and graphite are so different? • Due to the difference in the arrangement of carbon atoms in diamond and graphite
Hydrocarbons • Hydrocarbons are compounds of carbon and hydrogen. The natural source of hydrocarbons is petroleum (crude oil)
The Simplest Hydrocarbon A molecule of methane has four hydrogen atoms linked to one central atom of carbon. Methane CH4
Hydrocarbons Saturated Alkanes
Alkanes • The hydrocarbons methane, ethane propane and butane form a series of carbon compounds known as alkanes • The alkane series can be represented by the general formula
Isomerism • Compounds having the same molecular formulae but different structural arrangement of atoms in them are known as isomers, and the phenomenon is known as isomerism Isomers of Butane – Obtained by rearranging the carbon and the hydrogen atoms
Unsaturated Hydrocarbons • Unsaturated hydrocarbons contain a double or triple bond between two carbon atoms. • The one with double bond are called alkenes
Alkynes • Unsaturated hydrocarbons which contain triple bond between two carbon atoms.