KEY NOTES – Carbon-Class 10 – Science -Chemistry -Chapter 4 – Carbon and its Compounds

KEY NOTES – Carbon-Class 10 – Science -Chemistry -Chapter 4 – Carbon and its Compounds

Introduction to Carbon:

• Carbon is a versatile element with the unique ability to form a vast number of compounds.
• All living organisms, including plants and animals, contain carbon compounds.
• Bonding in Carbon Carbon form covalent bonds.
•  Formation of covalent bond : Covalent bond formation involves sharing of electrons between bonding atoms which may be either same or different. Covalency : The number of electrons contributed by an atom for sharing is known as its covalency.

Characteristics of covalent compounds :

(i)             These compounds are molecular in nature (i.e. they exist as single molecules)

(ii)           These are insoluble in water and soluble in benzene, kerosene and petrol etc.

(iii)         These compounds are poor conductor of electricity. 

Allotropes of Carbon:

Different forms of an element that have same chemical properties but different physical properties are known as Allotropes.

a. Diamond:

Structure: Tetrahedral arrangement of carbon atoms, with each carbon forming four strong covalent bonds.

Properties:

Extremely hard and durable.

Excellent thermal conductivity.

Transparent and exhibits high refractive index, contributing to its brilliance.

Non-conductive of electricity.

b. Graphite:

Structure: Hexagonal layers of carbon atoms arranged in planes, with weak van der Waals forces between layers.

Properties:

Soft and slippery due to the ability of layers to slide over each other.

Good conductor of electricity due to the delocalized electrons in the pi bonds.

High thermal conductivity.

Used as a lubricant and in pencil “leads.”

c. Fullerenes:

Structure: Hollow spheres, ellipsoids, or tubes composed entirely of carbon atoms.

Properties:

C60 (Buckminsterfullerene):

Spherical shape resembling a soccer ball.

Exhibits unique electronic properties.

Used in nanotechnology and as a cage for other atoms or molecules.

Fullerene:  C60, also known as Buckminsterfullerene, is the most common form of fullerenes. It has carbon atoms arranged in the shape of a football.

Versatile nature of carbon

Carbon is included in ten formation of a variety of compounds. This is due to the following two reasons:

(i) Catenation: Carbon has the unique ability to form covalent bonds with other atoms of carbon, giving rise to large molecules. This property is called catenation.

Carbon exhibits catenation property due to the following reasons:

Size of the carbon atom is very small. This enables its nucleus to hold the shared pair of electrons strongly.

The carbon-carbon bond is quite strong.

(ii) Tetravalency:

Carbon has four valence electrons, allowing it to form up to four covalent bonds.

This characteristic enables carbon to create stable molecules by sharing electrons with other atoms.

Hydrocarbons

Compounds of carbon and hydrogen are known as hydrocarbons.

For example – Methane (CH4), Ethane (C2H6), etc.

Saturated hydrocarbons: These hydrocarbons have all carbon-carbon single bonds. These are known as alkanes.

General formula = CnH2n+2

where n = number of carbon atoms

Unsaturated hydrocarbons: These hydrocarbons have at least one carbon-carbon double or triple bond.

Hydrocarbons with carbon-carbon double bond are known as alkenes. General formula = CnH2n

Hydrocarbons with carbon-carbon triple bond are known as alkynes. General formula = CnH2n-2

Homologous Series:

Organic compounds with the same functional group belong to a homologous series.

Members of a homologous series share a similar structure and exhibit a gradation in physical and chemical properties.

 Example: Alkane Homologous Series (Saturated Hydrocarbons):

General Formula: CnH2n+2 (where n is the number of carbon atoms)

Common Functional Group: Single bonds (C-C)

Example Members:

Methane (CH4)

Ethane (C2H6)

Propane (C3H8)

Butane (C4H10)