A Comprehensive Guide to Carbon and Its Compounds for CBSE Class 10 Science Students at Future Classes
Carbon is one of the most important elements in the periodic table, and its compounds are extremely important in all aspects of life. In CBSE Class 10 Science, students learn about the properties of carbon, its compounds, and their uses. Carbon has the ability to form strong covalent bonds with other elements, allowing it to form a wide variety of compounds. These compounds can be used for a variety of purposes, including fuels, plastics, and medicines. Students learn about the different properties of carbon compounds and how they can be used in everyday life. Additionally, students study the chemical reactions of carbon and its compounds to gain an understanding of their structure and reactivity.
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Chapter - 4 Carbon and its compounds
Introduction:
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The element carbon is non-metal. Its symbol is C.
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Carbon is versatile element present in earth crust in form of mineral is 0.02% and atmosphere as carbon dioxide is 0.03%.
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All the living things, plants and animals are made up of carbon-based compounds.
Covalent bonding in carbon compounds
The atomic number of carbons is 6.
Electronic configuration:
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Carbon is tetravalent, it does not form ionic bond by either losing four electrons or by gaining four electrons. It is difficult to hold four extra electron and would require large amount of energy to remove four electrons. So, carbon can form bond by sharing of its electrons with the electrons of other carbon atom or with other element and attain noble gas configuration.
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The atoms of other elements like hydrogen, oxygen and nitrogen, chlorine also form bonds by sharing of electrons.
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The bond formed by sharing of electrons between same or different atoms is covalent bond.
Examples of covalent bonding
Formation of methane
Formation of water molecules
Properties of Covalent Compounds
The compounds containing covalent bonds are called covalent compounds. They have following properties i.e.
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Covalent compounds have low melting and boiling points due to small intermolecular forces of attraction between the atoms.
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Covalent compounds are generally poor conductors of electricity. This is because the electrons are shared between atoms and no charged particles are formed in these compounds.
Versatile Nature of Carbon
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Catenation The property of self-linking of elements mainly C-atoms through covalent bonds to form long, straight or branched chains and rings of different sizes is called catenation.
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Tetravalency of carbon the valency of carbon is four, i.e., it is capable of bonding or pairing with four other carbon atoms or with the atoms of some other monovalent elements like hydrogen, halogen (chlorine, bromine), etc.
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Tendency to form multiple bonds Carbon has a strong tendency to form multiple bonds due to its small size. It shares more than one electron pair with its own atoms or with the atoms of elements like oxygen, nitrogen, Sulphur, etc.
Organic Compounds
The compounds of carbon except its oxides, carbonates and hydrogen carbonate salts, are known as organic compounds.
Hydrocarbons
Organic compounds made up of carbon and hydrogen are called hydrocarbons. These are of two types, i.e.
Saturated Hydrocarbons
Saturated hydrocarbons arc called alkane or paraffin. All the carbon atoms in these are bonded through single bonds. The general formula of these compounds is CnH2n+2 and suffix – “ane" is used in their nomenclature.
e.g., CH4 (methane), C2H6 (ethane), etc.
Unsaturated Hydrocarbons
Those compounds in which at least one double or triple bond is present between two carbon atoms are called unsaturated hydrocarbons.
Aliphatic unsaturated hydrocarbons are of two types
Alkene Those hydrocarbons which have at least one carbon-carbon double bond are called alkenes or olefins. The general formula of these compounds is CnH2n and suffix “ene”. e.g., C2H4 (ethene).
Alkyne those hydrocarbons which must have at least one carbon-carbon triple bond are called alkyne. The general common formula of these compound is CnH2n-n and suffix “yne”, e.g., C2H2 (ethyne).
Electron Dot Structure of Saturated Hydrocarbons
Ethane C2H6
Ethane C2H6
Electron dot structure of unsaturated hydrocarbons
Electron Dot Structure of Saturated Hydrocarbons
In some compounds, carbon atoms are arranged in the form of ring. E.g., cyclohexane and benzene.
Isomerism
Organic compounds with same molecular formula but different chemical and physical properties are called isomers. This phenomenon is called isomerism.
e.g., two structural isomers are possible for butane.
Functional Groups
Groups which combine with a carbon chain and decide its chemical properties are called functional groups.
Homologous Series
It is series of compounds in which some functional group substitutes for the hydrogen in a carbon chain.
E.g., Alcohols - CH3OH, C2H5OH, C3H7OH, C4H9OH
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Have same general formula.
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Any two homologues differ by – CH2 group.
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Have same chemical properties but show gradual change in physical properties.
Nomenclature of Carbon Compounds
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Identify the number of carbon atoms in compounds.
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Functional group is indicated by suffix or prefix.
Nomenclature of Carbon Compounds
Combustion
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Carbon and its compounds are used as fuels because they burn in air releasing lot of heat energy.
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Saturated hydrocarbon generally burns in air with blue and non-sooty flame.
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Unsaturated hydrocarbon burns in air with yellow sooty flame because percentage of carbon is higher than saturated hydrocarbon which does not get completely oxidized in air.
Oxidation
Alcohols can be converted to carboxylic acid in presence of oxidizing agent alkaline KMnO4 (potassium permanganate) or acidic potassium dichromate.
Addition Reaction:
Alcohols can be converted to carboxylic acid in presence of oxidizing agent alkaline KMnO4 (potassium permanganate) or acidic potassium dichromate.
Substitution Reaction:
Important Carbon Compounds: Ethanol and Ethanoic acid
Physical Properties of Ethanol
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Colorless, pleasant smell and burning taste
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Soluble in water.
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Volatile liquid with low boiling point of 351 K.
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Neutral compound.
Chemical Properties
Reaction with Sodium:
This reaction is used as a test for ethanol by evolution of H2 gas (Burn with pop sound).
Dehydration:​​
Physical Properties of Ethanoic acid
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Colorless liquid having sour taste and have smell of vinegar.
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Boiling point is 391 K.
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When pure Ethanoic acid is freeze, it forms colorless ice like solid. So, it is called glacial acetic acid.
Chemical Properties
Dehydration:​​
Reaction with base:
Soaps and Detergents
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Soap is sodium or potassium salt of long chain carboxylic acid. E.g., C17H35COO-Na+
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Soaps are effective only in soft water.
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Detergents are ammonium or sulphonate salt of long chain of carboxylic acid.
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Detergents are effective in both hard and soft water.
Soap molecule has:
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Ionic (hydrophyllic) part
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Long hydrocarbon chain (hydrophobic) part
Soaps and Detergents
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Most dirt is oily in nature and hydrophobic end attaches itself with dirt and the ionic end is surrounded with molecule of water. This result information of a radial structure called micelles.
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Soap micelles helps to dissolve dirt and grease in water and cloth gets cleaned.
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The magnesium and calcium salt present in hard water react with soap molecule to form insoluble product called scum. This scum create difficulty in cleansing action.
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By use of detergent, insoluble scum is not formed with hard water and cloths get cleaned effectively.
