10th Class Science Carbon and its Compounds / कार्बन और उसके यौगिक Crabon and Its Compounds

 Carbon and Its Compounds

• Carbon is a non-metal. All living things, plants and animals are made up of carbon based compounds which are called organic compounds.

We can test the presence of carbon in a material on the basis of the fact that carbon and its compounds burn in air to give carbon dioxide gas which turns lime water milky.

• The atomic number of carbon is 6, i.e., K shell has 2 electrons and L shell has 4 electrons.

• Occurrence of Carbon

Carbon occurs in nature in the 'free state' (as element) as well as in the 'combined state' (in the form of compounds with other elements).

• Allotropes of Carbon

The three allotropes of carbon are diamond, graphite and buck minster fullerene.

• Catenation and Tetravalency

• The two characteristic properties of carbon which leads to the formation of o very large number of organic compounds are catenation and tetravalency.

• Carbon atoms can link with one another by means of covalent bonds to form long chains (or rings) of carbon atoms.

• When carbon atoms combine with one another, three types of chains are formed. These are : (i) straight chains, (ii) branched chains, and (iii) closed chains or ring type chains.

• Hydrocarbons

Hydrocarbons are compounds of carbon and hydrogen. They can be saturated or unsaturated.

• Saturated Hydrocarbons (Alkanes)

• A hydrocarbon in which carbon atoms are bonded to hydrogen atoms by only single bonds is called a saturated hydrocarbon. Saturated hydrocarbons are also called alkanes.

• Unsaturated Hydrocarbons (Alkenes and Alkynes)

A hydrocarbon in which two carbon atoms are bonded by a 'double bond' or a 'triple bond' is called an unsaturated hydrocarbon. Ethene \[({{H}_{2}}C=C{{H}_{2}})\]and ethyne\[(HC\equiv CH)\]are two important unsaturated hydrocarbons, because ethene contains a double bond and ethyne contains a triple bond between two carbon atoms.

• Isomers

The organic compounds having the same molecular formula but different structures are known as isomers. Isomerism is possible only with hydrocarbons having 4 or more carbon atoms.

• Normal-butane has a straight chain structure whereas iso-butane has a branched chain structure.

• Homologous series

A homologous series is a group of organic compounds having similar structures and similar chemical properties in which the successive compounds differ by - CK, group.

• Coal and petroleum

Coal is a complex mixture of compounds of carbon, hydrogen and oxygen, and some free carbon. Small amounts of nitrogen and sulphur compounds are also present in coal.

• Petroleum is a complex mixture of several solid, liquid and gaseous hydrocarbons mixed with water, salt and several particles present in earth's crust.

• Petroleum oil (and natural gas) were formed by the decomposition of the remains of extremely small plants and animals buried under the sea millions of years ago.

• Chemical properties of carbon compounds:

(i) Combustion or burning: Alkanes burn in air to produce a lot of heat due to which alkanes are excellent fuels.

(ii) Substitution Reactions: Saturated hydrocarbons, however, undergo substitution reactions with chlorine in the presence of sunlight.

(iii) Addition Reactions are undergone by all unsaturated hydrocarbons containing a double bond or a triple bond like the alkenes and alkynes.

• Functional groups

Some of the important functional groups are

• Soaps and detergents

            Soaps and detergents are sodium salts of different organic acids (or) fatty acids.