Lakhmir Singh and Manjit Kaur Class 10 Chemistry Chapter-4 Carbon and its Compounds
Students preparing for board exams often rely on Lakhmir Singh and Manjit Kaur Class 10 Chemistry because it explains every concept in a simple and exam-friendly way. This chapter on Carbon and its Compounds is one of the most important units in Class 10 Science, covering bonding, hydrocarbons, functional groups, soaps, detergents, and chemical reactions. Many learners also search for Lakhmir Singh Solutions to understand textbook questions, numerical problems, and practice exercises in a step-by-step manner.
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Introduction to Carbon and its Compounds
Carbon is a unique element found in all living organisms and many non-living substances. It has atomic number 6 and belongs to Group 14 of the periodic table. Carbon forms a vast number of compounds because of two special properties: catenation and tetravalency. Catenation means the ability of carbon atoms to join with one another and form long chains, branched chains, or rings. Tetravalency means carbon has valency four and can form four covalent bonds.
This chapter helps students understand why carbon chemistry is so vast and useful in everyday life. Fuels, plastics, medicines, food substances, fibers, and cleaning products all contain carbon compounds.
Covalent Bonding in Carbon
Carbon usually forms covalent bonds by sharing electrons with other atoms. Since losing or gaining four electrons requires too much energy, carbon prefers sharing electrons. This results in stable molecules such as methane, ethane, and carbon dioxide.
Examples of covalent compounds:
- Methane (CH4)
- Ethane (C2H6)
- Water (H2O)
- Carbon dioxide (CO2)
Covalent compounds generally have low melting and boiling points and do not conduct electricity.
Allotropes of Carbon
Carbon exists in different physical forms known as allotropes. These allotropes have different structures and properties.
Crystalline Allotropes
- Diamond – hardest natural substance, used in cutting tools
- Graphite – soft and slippery, used in pencils and lubricants
- Fullerene – spherical molecules made of carbon atoms
Amorphous Allotropes
- Coal
- Charcoal
- Coke
- Lampblack
These forms are important in industries and daily life.
Saturated and Unsaturated Hydrocarbons
Hydrocarbons are compounds made only of carbon and hydrogen.
Saturated Hydrocarbons
These contain only single bonds between carbon atoms. They are called alkanes.
Examples:
- Methane
- Ethane
- Propane
Unsaturated Hydrocarbons
These contain double or triple bonds.
Examples:
- Ethene (double bond)
- Ethyne (triple bond)
Unsaturated compounds are more reactive than saturated compounds.
Homologous Series
A homologous series is a group of organic compounds with the same functional group and similar chemical properties. Successive members differ by CH2.
Examples of alkane series:
- Methane (CH4)
- Ethane (C2H6)
- Propane (C3H8)
- Butane (C4H10)
This topic is important for naming compounds and understanding patterns in organic chemistry.
Functional Groups
Functional groups are atoms or groups of atoms that determine the chemical behavior of compounds.
Common functional groups:
- Alcohol: –OH
- Aldehyde: –CHO
- Carboxylic acid: –COOH
- Ketone: –CO–
- Halogen: –Cl, –Br, –I
For example, ethanol contains the –OH group and behaves as an alcohol.
Important Chemical Reactions of Carbon Compounds
Combustion
Carbon compounds burn in air to produce carbon dioxide, water, heat, and light.
Example: Methane burns with a blue flame.
Oxidation
Alcohols can be oxidized to acids using oxidizing agents.
Addition Reaction
Unsaturated compounds add hydrogen in the presence of catalysts such as nickel.
Example: Vegetable oil changes into ghee.
Substitution Reaction
In saturated hydrocarbons, one atom is replaced by another atom.
Example: Methane reacts with chlorine in sunlight.
Soaps and Detergents
Soaps are sodium or potassium salts of fatty acids. They are made by the reaction of fats or oils with sodium hydroxide. This process is called saponification.
Soap molecules have:
- Hydrophilic end (water-attracting)
- Hydrophobic end (oil-attracting)
They form micelles that trap dirt and grease.
Detergents are synthetic cleansing agents that work even in hard water. They are more effective than soaps in areas where water contains calcium or magnesium salts.
Importance of Carbon Compounds in Daily Life
Carbon compounds are present everywhere:
- Petrol and diesel as fuels
- Plastics for packaging
- Medicines and vitamins
- Perfumes and cosmetics
- Food substances like sugar and proteins
- Synthetic fibers like nylon and polyester
Understanding this chapter builds a strong base for higher chemistry studies.
Why Students Prefer This Chapter Guide
Students prefer this chapter because it combines theory with practical examples. Topics like soaps, fuels, and plastics connect chemistry to real life. The chapter also contains many board exam questions based on reactions, definitions, and naming of compounds.