This document discusses carbon and its compounds. Carbon has four electrons in its outer orbit and can form four covalent bonds, giving it a valency of four. It is a non-metal that occurs naturally in two allotropes - diamond and graphite. While diamond and graphite are chemically identical, consisting entirely of carbon, they have very different physical properties due to differences in how the carbon atoms are arranged. Carbon has the unique ability to form long chains, providing a backbone for other atoms to attach to, resulting in the vast number and variety of carbon compounds found in nature, including hydrocarbons.

1. CARBON AND ITS COMPOUNDS

2. 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.

3. Compounds of Carbon are Widely
Distributed in Nature
 The number of carbon compounds is
larger than that of all other elements put
together.

4. 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

5. 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

6. Allotropes of Carbon
 In nature, pure carbon occur in two forms-
 Diamond
 Graphite

7. 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.

8. Physical Properties of
Diamond and Graphite
Property Diamond Graphite
Appearance Transparent Black, Shiny
Hardness Very Hard Soft, slippery to
touch
Thermal
Conductivity
Very poor moderate
Electrical
Conductivity
Poor Good conductor
Density(kg/m3) 3510 2250
Uses Jewellery, drilling Dry cell, electric
arc, lubricant,
pencil lead

9. 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.

10. 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

11. Hydrocarbons
 Hydrocarbons are compounds of carbon
and hydrogen.
The natural source of
hydrocarbons is
petroleum (crude oil)

12. The Simplest Hydrocarbon
Methane CH4
A molecule of
methane has four
hydrogen atoms
linked to one central
atom of carbon.

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14. 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

15. 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

16. Unsaturated Hydrocarbons
 Unsaturated hydrocarbons contain a
double or triple bond between two carbon
atoms.
 The one with double bond are called
alkenes

17. Alkenes

18. Alkynes
 Unsaturated hydrocarbons which contain
triple bond between two carbon atoms.