CARBON AND ITS COMPOUNDS

Allotropes of Carbon In nature, pure carbon occur in two forms- Diamond  Graphite...  Diamond and Graphite – two allotropes of carbon differ in their physical properties... Physical

CARBON AND ITS COMPOUNDS

 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

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

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 are compounds of carbon and hydrogen

The natural source of

hydrocarbons is

petroleum (crude oil)

The Simplest Hydrocarbon

Methane CH4

methane has four

linked to one central

atom of carbon

y

d

r

o

c

a

r

b

S

a

t

u

r

a

t

e

d

A l k a n e s

 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

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

Alkenes

 Unsaturated hydrocarbons which contain triple bond between two carbon atoms