Class 10 Science Notes Chapter 4: Carbon and its Compounds

Carbon is one of the most important elements in chemistry because it forms the basis of all living organisms and millions of compounds used in everyday life. Its unique ability to form strong covalent bonds with itself and other elements gives rise to an enormous variety of organic compounds. 

These Class 10 notes Chapter 4 Carbon and Its Compounds are designed according to the latest syllabus to help students understand concepts clearly and prepare confidently for exams. 

Topics Covered in Class 10 Science Notes Chapter 4 Carbon and Its Compounds 

What are Carbon and Its Compounds?	Nomenclature of Carbon Compounds
Versatile Nature of Carbon	Chemical Properties of Carbon Compounds
Covalent Bonding in Carbon	Ethanol
Homologous Series	Ethanoic Acid
Functional Groups	Soaps and Detergents

Class 10 Science Chapter 4: Carbon and Its Compounds

What are Carbon and Its Compounds

Carbon is a unique element that forms the backbone of all living organisms and countless substances used in everyday life. It has the chemical symbol C and atomic number 6. Unlike most elements, carbon can combine with itself and many other elements such as hydrogen, oxygen, nitrogen, sulphur and chlorine to form millions of compounds.

Carbon compounds are present in fuels, medicines, plastics, food, fibres, detergents and many other products that we use daily. The enormous variety of carbon compounds is possible because of two special properties of carbon tetravalency and catenation.

Versatile Nature of Carbon

Carbon is called a versatile element because it can form a large number of stable compounds.

Tetravalency

Carbon has four electrons in its outermost shell. Instead of gaining or losing four electrons, it shares them with other atoms to complete its octet. Therefore, carbon forms four covalent bonds, making it tetravalent.

Catenation

Carbon atoms can bond with one another to form long chains, branched chains and ring structures. This self-linking property is known as catenation.

Because of catenation, carbon forms compounds of different sizes and structures, resulting in millions of organic compounds.

Covalent Bonding in Carbon

Carbon generally forms covalent bonds by sharing electrons with other atoms.

In a covalent bond:

• Electrons are shared instead of transferred.
• Molecules remain electrically neutral.
• Covalent compounds usually have low melting and boiling points.
• They are poor conductors of electricity because they do not contain free ions.

Examples include:

• Methane (CH₄)
• Water (H₂O)
• Carbon dioxide (CO₂)

The shared electrons help each atom achieve a stable electronic configuration.

Characteristics of Covalent Compounds

Include points such as:

• They usually have low melting and boiling points.
• Most covalent compounds are poor conductors of electricity because they do not contain free-moving ions.
• They are generally insoluble in water but dissolve easily in organic solvents such as benzene and ether.
• Many covalent compounds exist as gases or liquids, while some are soft solids.
• They usually have weaker intermolecular forces than ionic compounds, making them easier to melt or boil.

Allotropes of Carbon

Allotrope	Characteristics	Uses
Diamond	Hardest natural substance	Cutting tools, jewellery
Graphite	Good conductor of electricity	Electrodes, lubricants
Fullerene	Cage-like carbon structure	Nanotechnology, research

Homologous Series

A homologous series is a family of organic compounds having the same functional group and similar chemical properties.

Successive members differ by a -CH₂ group, which increases the molecular mass by 14 u.

Characteristics of a Homologous Series

• Same functional group
• Similar chemical properties
• Gradual change in physical properties
• Similar methods of preparation

Example: Alcohols

Compound	Molecular Formula
Methanol	CH₃OH
Ethanol	C₂H₅OH
Propanol	C₃H₇OH
Butanol	C₄H₉OH

As the number of carbon atoms increases, the boiling and melting points also increase.

Functional Groups

A functional group is an atom or group of atoms that determines the chemical properties of an organic compound.

Some common functional groups are:

Functional Group	Suffix
Alcohol	-ol
Aldehyde	-al
Ketone	-one
Carboxylic Acid	-oic acid
Alkene	-ene
Alkyne	-yne

The functional group is responsible for the characteristic reactions of carbon compounds.

Nomenclature of Carbon Compounds

Organic compounds are named according to IUPAC rules.

The basic steps are:

1. Count the number of carbon atoms.
2. Identify the longest carbon chain.
3. Identify the functional group.
4. Add the appropriate prefix or suffix.

For example:

• CH₃OH → Methanol
• CH₃CH₂OH → Ethanol
• CH₃COOH → Ethanoic acid

This systematic naming method ensures that each compound has a unique name.

Difference Between Saturated and Unsaturated Hydrocarbons

Hydrocarbons are classified as saturated or unsaturated based on the type of bonds present between carbon atoms.

Saturated Hydrocarbons	Unsaturated Hydrocarbons
Contain only single covalent bonds	Contain one or more double or triple bonds
Less reactive	More reactive
Undergo substitution reactions	Undergo addition reactions
Known as alkanes	Include alkenes and alkynes
Burn with a clean blue flame	Often burn with a yellow, smoky flame

Chemical Properties of Carbon Compounds

Carbon compounds undergo several important chemical reactions.

Combustion

Carbon compounds burn in oxygen to produce carbon dioxide, water, heat and light.

Example:  $CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O + \text{Heat}$

Complete combustion produces a blue flame, while incomplete combustion produces a yellow, smoky flame and soot. Fuels containing sulphur and nitrogen may also release harmful pollutants during combustion.

Oxidation

Oxidation involves the addition of oxygen or the removal of hydrogen.

$\mathrm{CH_3CH_2OH + 2[O] \xrightarrow{\text{Acidified } K_2Cr_2O_7 \text{ or Alkaline } KMnO_4} CH_3COOH + H_2O}$

Alcohols are oxidised into carboxylic acids using oxidising agents such as:

• Acidified potassium dichromate
• Alkaline potassium permanganate

These substances supply oxygen during the reaction and convert alcohols into acids.

Addition Reaction

Unsaturated hydrocarbons undergo addition reactions. Hydrogen is added across double or triple bonds in the presence of catalysts like nickel or palladium.

$\mathrm{CH_2=CH_2 + H_2 \xrightarrow{Ni/Pd} CH_3-CH_3}$

This process is known as hydrogenation and is used to convert vegetable oils into vanaspati ghee.

$\mathrm{Vegetable\ Oil + H_2 \xrightarrow{Ni} Vanaspati\ Ghee}$

Substitution Reaction

Saturated hydrocarbons undergo substitution reactions.

Example:

$CH_4 + Cl_2 \xrightarrow{\text{Sunlight}} CH_3Cl + HCl$

In this reaction, chlorine replaces a hydrogen atom in methane.

Ethanol

Ethanol (C₂H₅OH) is a colourless liquid commonly known as alcohol.

Properties

• Soluble in water
• Good solvent
• Used in medicines, perfumes, sanitizers and industries

Reactions of Ethanol

Reaction with Sodium

$2Na + 2C_2H_5OH \rightarrow 2C_2H_5ONa + H_22Na$

Hydrogen gas is evolved during this reaction.

Dehydration

When ethanol is heated with concentrated sulphuric acid, it loses water and forms ethene.

$C_2H_5OH \rightarrow C_2H_4 + H_2O$

Excessive consumption of ethanol can adversely affect the nervous system and overall health.

Ethanoic Acid

Ethanoic acid (CH₃COOH), commonly called acetic acid, is the main component of vinegar.

Properties

• Weak acid
• Colourless liquid
• Sour smell
• Used as a food preservative

Important Reactions

Reaction with Base

$CH_3COOH + NaOH \rightarrow CH_3COONa + H_2O$

Esterification

Ethanoic acid reacts with ethanol in the presence of concentrated sulphuric acid to form a pleasant-smelling ester.Esters are widely used in perfumes, food flavourings and cosmetics.

Soaps and Detergents

Soap molecules have two ends:

• Hydrophilic end (attracted to water)
• Hydrophobic end (attracted to oil)

These molecules form micelles, which trap oily dirt inside and remove it during washing.

Soap	Detergent
Forms scum in hard water	Works well in hard water
Made from fatty acids	Made from sulphonic acids
Biodegradable	Some detergents are non-biodegradable

Detergents are more effective in hard water because they do not form insoluble precipitates with calcium and magnesium ions.

Applications of Carbon Compounds

Carbon compounds are essential in everyday life and are used across a wide range of industries.Some important applications include:

• It is used as fuels such as LPG, petrol, diesel and natural gas.
• It is used in the manufacture of plastics, synthetic fibres and rubber.
• Ethanol is widely used in medicines, perfumes, hand sanitisers and industrial solvents.
• Ethanoic acid is used as a food preservative and in the manufacture of chemicals.
• Carbon compounds are used to produce detergents, soaps, dyes and cosmetics.
• Many medicines and pharmaceutical products are based on carbon compounds.