Carbon and its Compounds Class 10 || Science|| Chapter 4 Notes

Carbon and its Compounds Class 10 ||Science|| Chapter 4 Notes

1. Introduction to Carbon

Atomic Number: 6
Electronic Configuration: $2, 4$
Valency: 4 (tetravalent)
Carbon has four electrons in its outermost shell, so it requires four more to achieve a stable electronic configuration. This tetravalency allows carbon to form covalent bonds with a variety of atoms, leading to an enormous number of compounds.

2. Covalent Bonding in Carbon

Carbon forms covalent bonds by sharing electrons with other atoms. Covalent bonds can be:
Single bond: Sharing one pair of electrons (e.g., between two hydrogen atoms and one carbon atom in methane, $C H_{4}$ ).
Double bond: Sharing two pairs of electrons (e.g., between two carbon atoms in ethene, $C_{2} H_{4}$ ).
Triple bond: Sharing three pairs of electrons (e.g., between two carbon atoms in ethyne, $C_{2} H_{2}$ ).
Covalent compounds generally have low melting and boiling points, do not conduct electricity, and are usually poor conductors of heat.

3. Versatile Nature of Carbon

The ability of carbon to form a wide variety of compounds is due to the following properties:

1. Catenation

Catenation is the property of carbon atoms to form long chains, branched chains, or even rings by bonding with other carbon atoms. This allows carbon to form numerous complex structures, including straight chains, branched chains, and rings.

2. Tetravalency

Carbon can bond with four other atoms, which can be other carbon atoms or atoms of elements like hydrogen, oxygen, nitrogen, etc., forming diverse compounds.

3. Formation of Multiple Bonds

Carbon can form single, double, or triple bonds with other carbon atoms or with atoms of other elements, giving rise to a wide variety of organic compounds.

4. Allotropes of Carbon

Allotropes are different forms of the same element in the same physical state. Carbon has several allotropes, the most important being:

1. Diamond

In diamond, each carbon atom is bonded to four other carbon atoms in a tetrahedral structure.
Diamond is extremely hard and has a very high melting point.
It does not conduct electricity as there are no free electrons.

2. Graphite

In graphite, each carbon atom is bonded to three other carbon atoms in hexagonal layers, and one electron is free to move.
Graphite is soft, slippery, and a good conductor of electricity due to the presence of free electrons.
It is used in pencils (as lead) and as a lubricant.

3. Fullerenes

Fullerenes are spherical molecules made entirely of carbon, with a structure resembling a soccer ball (e.g., Buckminsterfullerene, $C_{60}$ ).

5. Hydrocarbons

Hydrocarbons are compounds composed only of carbon and hydrogen atoms. They are classified into two types:

1. Saturated Hydrocarbons (Alkanes)

In saturated hydrocarbons, carbon atoms are bonded to each other by single covalent bonds.
The general formula for alkanes is $C_{n} H_{2 n + 2}$ .
Example: Methane ( $C H_{4}$ ), Ethane ( $C_{2} H_{6}$ ).

2. Unsaturated Hydrocarbons

Alkenes: Hydrocarbons with one or more double bonds between carbon atoms. The general formula for alkenes is $C_{n} H_{2 n}$ . Example: Ethene ( $C_{2} H_{4}$ ).
Alkynes: Hydrocarbons with one or more triple bonds between carbon atoms. The general formula for alkynes is $C_{n} H_{2 n - 2}$ . Example: Ethyne ( $C_{2} H_{2}$ ).

6. Functional Groups

In organic chemistry, specific groups of atoms impart distinct properties to molecules. These are called functional groups. Some important functional groups are:
Alcohol group: $- O H$ (Hydroxyl group) — Example: Ethanol ( $C H_{3} C H_{2} O H$ ).
Aldehyde group: $- C H O$ — Example: Ethanal ( $C H_{3} C H O$ ).
Carboxylic acid group: $- C O O H$ — Example: Ethanoic acid ( $C H_{3} C O O H$ ).
Ketone group: $- C O -$ — Example: Propanone ( $C H_{3} C O C H_{3}$ ).
Halogen group: $- X$ (X = Cl, Br, I) — Example: Chloromethane ( $C H_{3} C l$ ).

7. Homologous Series

A homologous series is a series of organic compounds having the same functional group and similar chemical properties. The successive members of a homologous series differ by a –CH₂ group.
For example, in the alkane series:
Methane: $C H_{4}$
Ethane: $C_{2} H_{6}$
Propane: $C_{3} H_{8}$
Each member has a difference of $C H_{2}$ and has predictable physical and chemical properties.

8. Chemical Properties of Carbon Compounds

1. Combustion

Carbon compounds burn in the presence of oxygen to produce carbon dioxide, water, and energy.
Example: Combustion of methane $C H_{4} + 2 O_{2} \to C O_{2} + 2 H_{2} O + heat$

2. Oxidation

Oxidation of alcohols can produce carboxylic acids. For example:
$C H_{3} C H_{2} O H \overset{a l k . K M n O_{4}}{\to} C H_{3} C O O H$

3. Addition Reaction

Unsaturated hydrocarbons (alkenes and alkynes) can undergo addition reactions with hydrogen (hydrogenation) to form saturated hydrocarbons.
Example: Ethene reacts with hydrogen in the presence of a catalyst to form ethane. $C_{2} H_{4} + H_{2} \overset{N i}{\to} C_{2} H_{6}$

4. Substitution Reaction

In saturated hydrocarbons, a hydrogen atom can be replaced by a halogen (such as chlorine).
Example: Methane reacts with chlorine in the presence of sunlight to form chloromethane. $C H_{4} + C l_{2} \overset{s u n l i g h t}{\to} C H_{3} C l + H C l$

9. Some Important Carbon Compounds

1. Ethanol (C₂H₅OH)

Ethanol is a commonly used alcohol.
It is a colorless liquid, soluble in water, and has a pleasant smell.
It is used as a solvent, in alcoholic beverages, and as a fuel (in biofuels like gasohol).

2. Ethanoic Acid (Acetic Acid, CH₃COOH)

Ethanoic acid is a weak acid found in vinegar.
Its chemical name is acetic acid.
Ethanoic acid reacts with alcohols to form esters in a reaction known as esterification.
$C H_{3} C O O H + C_{2} H_{5} O H \overset{c o n c . H_{2} S O_{4}}{\to} C H_{3} C O O C_{2} H_{5} + H_{2} O$
The ester formed has a fruity smell and is used in perfumes and flavorings.

10. Soaps and Detergents

1. Soaps

Soaps are sodium or potassium salts of long-chain fatty acids. They are prepared by the saponification reaction:
$F a t + N a O H \to S o a p + G l y c e r o l$
Soaps form micelles in water to clean greasy dirt.

2. Detergents

Detergents are synthetic cleaning agents that work well in hard water (water containing calcium or magnesium ions) because they do not form scum like soaps.

Summary:

Carbon is tetravalent, allowing it to form a variety of covalent compounds, including hydrocarbons and compounds with functional groups.
Catenation, tetravalency, and multiple bonding are key properties contributing to the vast number of carbon compounds.
Carbon forms allotropes like diamond, graphite, and fullerenes.
Carbon compounds can undergo reactions such as combustion, oxidation, addition, and substitution.
Ethanol and ethanoic acid are important carbon compounds with widespread applications.
Soaps and detergents are used for cleaning, with detergents being more effective in hard water.
This chapter gives insight into the world of organic chemistry and carbon compounds, which have significant applications in daily life and industries.

Carbon and its Compounds Class 10 || Science|| Chapter 4 Notes

1. Introduction to Carbon

2. Covalent Bonding in Carbon

3. Versatile Nature of Carbon

The ability of carbon to form a wide variety of compounds is due to the following properties:

1. Catenation

Catenation is the property of carbon atoms to form long chains, branched chains, or even rings by bonding with other carbon atoms. This allows carbon to form numerous complex structures, including straight chains, branched chains, and rings.

2. Tetravalency

Carbon can bond with four other atoms, which can be other carbon atoms or atoms of elements like hydrogen, oxygen, nitrogen, etc., forming diverse compounds.

3. Formation of Multiple Bonds

Carbon can form single, double, or triple bonds with other carbon atoms or with atoms of other elements, giving rise to a wide variety of organic compounds.

4. Allotropes of Carbon

Allotropes are different forms of the same element in the same physical state. Carbon has several allotropes, the most important being:

1. Diamond

In diamond, each carbon atom is bonded to four other carbon atoms in a tetrahedral structure.Diamond is extremely hard and has a very high melting point.It does not conduct electricity as there are no free electrons.

2. Graphite

In graphite, each carbon atom is bonded to three other carbon atoms in hexagonal layers, and one electron is free to move.Graphite is soft, slippery, and a good conductor of electricity due to the presence of free electrons.It is used in pencils (as lead) and as a lubricant.

3. Fullerenes

Fullerenes are spherical molecules made entirely of carbon, with a structure resembling a soccer ball (e.g., Buckminsterfullerene, C60C60​).

5. Hydrocarbons

Hydrocarbons are compounds composed only of carbon and hydrogen atoms. They are classified into two types:

1. Saturated Hydrocarbons (Alkanes)

In saturated hydrocarbons, carbon atoms are bonded to each other by single covalent bonds.The general formula for alkanes is CnH2n+2Cn​H2n+2​.Example: Methane (CH4CH4​), Ethane (C2H6C2​H6​).

2. Unsaturated Hydrocarbons

6. Functional Groups

7. Homologous Series

8. Chemical Properties of Carbon Compounds

1. Combustion

Carbon compounds burn in the presence of oxygen to produce carbon dioxide, water, and energy.Example: Combustion of methaneCH4+2O2→CO2+2H2O+heatCH4​+2O2​→CO2​+2H2​O+heat

2. Oxidation

Oxidation of alcohols can produce carboxylic acids. For example:CH3CH2OH→alk. KMnO4CH3COOHCH3​CH2​OHalk. KMnO4​​CH3​COOH

3. Addition Reaction

Unsaturated hydrocarbons (alkenes and alkynes) can undergo addition reactions with hydrogen (hydrogenation) to form saturated hydrocarbons.Example: Ethene reacts with hydrogen in the presence of a catalyst to form ethane.C2H4+H2→NiC2H6C2​H4​+H2​Ni​C2​H6​

4. Substitution Reaction

In saturated hydrocarbons, a hydrogen atom can be replaced by a halogen (such as chlorine).Example: Methane reacts with chlorine in the presence of sunlight to form chloromethane.CH4+Cl2→sunlightCH3Cl+HClCH4​+Cl2​sunlight​CH3​Cl+HCl

9. Some Important Carbon Compounds

1. Ethanol (C₂H₅OH)

Ethanol is a commonly used alcohol.It is a colorless liquid, soluble in water, and has a pleasant smell.It is used as a solvent, in alcoholic beverages, and as a fuel (in biofuels like gasohol).

2. Ethanoic Acid (Acetic Acid, CH₃COOH)

10. Soaps and Detergents

1. Soaps

Soaps are sodium or potassium salts of long-chain fatty acids. They are prepared by the saponification reaction:Fat+NaOH→Soap+GlycerolFat+NaOH→Soap+GlycerolSoaps form micelles in water to clean greasy dirt.

2. Detergents

Detergents are synthetic cleaning agents that work well in hard water (water containing calcium or magnesium ions) because they do not form scum like soaps.

Summary:

In diamond, each carbon atom is bonded to four other carbon atoms in a tetrahedral structure.
Diamond is extremely hard and has a very high melting point.
It does not conduct electricity as there are no free electrons.

In graphite, each carbon atom is bonded to three other carbon atoms in hexagonal layers, and one electron is free to move.
Graphite is soft, slippery, and a good conductor of electricity due to the presence of free electrons.
It is used in pencils (as lead) and as a lubricant.

Fullerenes are spherical molecules made entirely of carbon, with a structure resembling a soccer ball (e.g., Buckminsterfullerene, $C_{60}$ ).

In saturated hydrocarbons, carbon atoms are bonded to each other by single covalent bonds.
The general formula for alkanes is $C_{n} H_{2 n + 2}$ .
Example: Methane ( $C H_{4}$ ), Ethane ( $C_{2} H_{6}$ ).

Carbon compounds burn in the presence of oxygen to produce carbon dioxide, water, and energy.
Example: Combustion of methane $C H_{4} + 2 O_{2} \to C O_{2} + 2 H_{2} O + heat$

Oxidation of alcohols can produce carboxylic acids. For example:
$C H_{3} C H_{2} O H \overset{a l k . K M n O_{4}}{\to} C H_{3} C O O H$

Unsaturated hydrocarbons (alkenes and alkynes) can undergo addition reactions with hydrogen (hydrogenation) to form saturated hydrocarbons.
Example: Ethene reacts with hydrogen in the presence of a catalyst to form ethane. $C_{2} H_{4} + H_{2} \overset{N i}{\to} C_{2} H_{6}$

In saturated hydrocarbons, a hydrogen atom can be replaced by a halogen (such as chlorine).
Example: Methane reacts with chlorine in the presence of sunlight to form chloromethane. $C H_{4} + C l_{2} \overset{s u n l i g h t}{\to} C H_{3} C l + H C l$

Ethanol is a commonly used alcohol.
It is a colorless liquid, soluble in water, and has a pleasant smell.
It is used as a solvent, in alcoholic beverages, and as a fuel (in biofuels like gasohol).

Soaps are sodium or potassium salts of long-chain fatty acids. They are prepared by the saponification reaction:
$F a t + N a O H \to S o a p + G l y c e r o l$
Soaps form micelles in water to clean greasy dirt.