Cbse Class 10 Chemistry Chapter 4 Notes

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Class 10 Chemistry Chapter 4 Notes Pdf

Cbse Class 10 Chemistry Chapter 4 Notes Pdf

Allotropes of carbon

Carbon is capable of forming many allotropes due to its valency. Well-known forms of carbon include diamond and graphite

Diamond: Diamond is a well-known allotrope of carbon. The hardness and high dispersion of light of diamond makes it useful for both industrial applications and jewelry. Diamond is the hardest known natural mineral. This makes it an excellent abrasive and makes it hold polish and lustre extremely well. No known naturally occurring substance can cut (or even scratch) a diamond, except another diamond.

Graphite: Graphite conducts electricity, due to the delocalization of the pi bond electrons above and below the planes of the carbon atoms. These electrons are free to move, so they are able to conduct electricity. However, electricity is only conducted along the plane of the layers.

Buckminsterfullerene: They are named for the resemblance of their allotropic structure to the geodesic structures devised by the scientist and architect Richard Buckminster “Bucky” Fuller. Fullerenes are molecules of varying sizes composed entirely of carbon, which take the form of a hollow sphere, ellipsoid, or tube.

Versatile Nature of Carbon

The versatile nature of carbon can be best understood with its features such as, tetravalency and catenation. In this section let us learn more about the versatility of carbon. Carbon is a versatile element and is found in many different chemical compounds, including those found in space. Carbon is versatile because it can form single, double, and triple bonds. It can also form chains, branched chains, and rings when connected to other carbon atoms. The two characteristic features are seen in carbon, that is, tetravalency and catenation, put together give rise to a large number of compounds. Many have the same non-carbon atom or group of atoms attached to different carbon chains.

▪️ Catenation: The property of forming long chains by self-linking with other carbon atoms to form long chains, rings, double or triple bonds is called catenation.

▪️ Isomerism: Compounds with the same molecular formula but different structural formulas are called isomers. Isomerism commonly seen is due to differences in the arrangement of atoms or groups of atoms & is called structural isomerism.

1. Carbon: All living structures are carbon based. The amount of carbon present in the Earth’s crust and in the atmosphere is quite meagre. The Earth’s crust has only 0.02% carbon in the form of minerals (like carbonates, bicarbonates, coal and petroleum) and the atmosphere has 0.03% carbon dioxide.

2. Covalent Bond in Carbon

The atomic number of carbon is 6 and its electronic configuration is 2, 4.

To attain a noble gas configuration it could gain four more electrons in its valence shell or loose the four electrons from its valence shell.

It is difficult for an atom of carbon to either gain or lose electrons as it would be difficult to hold the extra electrons and would require a large amount of energy to remove four electrons.

Carbon attains the noble gas configuration by sharing its valence electrons with other atoms. Atoms of other elements like hydrogen, oxygen, nitrogen, chlorine also show sharing of valence electrons.

Carbon and its Compounds Class 10 Notes Science Chapter 4 1

It is evident that the number of shared pair of electrons can be one, two or three. Try making the structures of H2O and CH4.

Bond formed by the sharing of an electron pair between two atoms is called covalent bond.

Covalently bonded molecules have low melting and boiling points because of comparatively weaker intermolecular forces, unlike ionic compounds.

These molecules are generally poor conductors of electricity since no charged particles are formed.

3. Versatile Nature of Carbon Atoms

Two important properties which enable carbon to form enormously large number of compounds.

Carbon and its Compounds Class 10 Notes Science Chapter 4 2

(i) Catenation is property of carbon atom to form bonds with other atoms of carbon. Like carbon, silicon forms compounds with hydrogen which have chains upto seven or eight atoms of silicon.

The property of catenation is shown by other elements also but carbon exhibits this property to maximum extent. This is due to greater strength of carbon-carbon bond.

(ii) Tetravalency of the carbon atom: Carbon has four valence electrons (At. No. of C = 6, Electronic Configuration = 2, 4) since it can neither lose nor gain electrons to attain octet, it forms covalent bonds by sharing its four electrons with other atoms. This characteristic of the carbon atom, by virtue of which it forms four covalent bonds, is called the tetravalency of carbon.

Cbse Class 10 Chemistry Chapter 4 Notes Pdf