HBSE 10th Class Science Notes Chapter 4 Carbon and Its Compounds

Haryana State Board HBSE 10th Class Science Notes Chapter 4 Carbon and Its Compounds Notes.

Haryana Board 10th Class Science Notes Chapter 4 Carbon and Its Compounds

Carbon is a non-metallic element. Its symbol is C.

In spite of being present in such a small quantity, carbon is an extremely important element. All the living things, plants and animals are made up of carbon based compounds known as organic compounds.

The atomic number of carbon is 6. This makes the valency of carbon as 4. This makes carbon quite a unique element. Hence, carbon joins with other elements by sharing electrons and forming covalent bonds.

Types of bonds:

• Ionic bond: The bond that takes place between a metal and a non-metal is called an ionic bond. Bond between sodium (Na) metal and chlorine (Cl) non-metal to form NaCl, H₂SO₄, etc.
• Covalent bond: The bond that takes place between two non-metals is called an covalent bond. Bond between hydrogen (H) and hydrogen (H), Hydrochloric acid (HCl), methane (CH₄), etc.

Versatile Nature of Carbon:

Catenation:
Carbon has a unique ability to bond with other atoms of carbon and form long chain. This unique property of carbon is called catenation.

Bonding by carbon:
Carbon atom bonds with the help of three types of covalent bonds namely, single bond, double bond and triple bond.

The structures formed by the three types of covalent bonds of carbon can be of the following types:

• Normal chain
• Branched (Iso) chain or
• Cyclic chain

The two important properties of carbon that help it to form a large number of compounds are

• Catenation and
• Tetravalency.

Saturated and Unsaturated Carbon Compounds:

Hydrocarbons: Compounds containing hydrogen and carbon are called hydrocarbons.

Hydrocarbons having single covalent bonds between their carbon atoms are called saturated hydrocarbons. Alkanes are the main class of saturated hydrocarbons.

Hydrocarbons having either double or triple covalent bonds between their carbon atoms are called unsaturated hydrocarbons. Alkenes and alkynes are the main classes of unsaturated hydrocarbons.

Chains, Branches and Rinss

Isomers and isomerism:
Property of catenation possessed by carbon gives rise to a large number of compounds with different structural formula and different physical properties.

Organic compounds that have same molecular formula but different structural formula are called isomers and the phenomenon is called isomerism.

On the basis of their structures (arrangement of carbon atoms), hydrocarbon compounds can be classified into following three categories:

• Straight chain compounds
• Branched chain compounds
• Ring structures OR Cyclic compounds

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Heteroatom:

• The atom or group of atoms of an element that replaces hydrogen in a hydrocarbon is called an heteroatom.
• Oxygen (O), nitrogen (N), sulphur (S), halogens such as fluorine (F), chlorine (Cl), bromine (Br) and iodine (I)) are typical heteroatoms that replace hydrogen.

Functional groups:

• A heteroatom (i.e. an atom or a group of atoms) which imparts specific properties to the organic compound they are attached to is called a functional group.
• Thus, the functional group decides the physical and chemical properties of the carbon compound, irrespective of the length of the carbon chain. Halogen, alcohol, carboxylic acid, etc. are examples of functional groups.

Homologous Series

• The series of organic compounds in which a particular functional group attaches to the carbon chain in place of hydrogen atom is called a homologous series.
• Each compound of the homologous series differs from its previous or later compound by (CH₂). For example, the alkanes namely methane (CH₄), ethane (C₂H₆), propane (C₃H₈), etc.

Nomenclature of Carbon Compounds

IUPAC names:

• Organic compounds or hydrocarbons have two names, (a) Common name and (b) IUPAC name. IUPAC names are names given by IUPAC.
• Example: Methyl alcohol is a general (common) name where as methanol is its IUPAC name.

Chemical Properties of Carbon Compounds

Combustion:
Carbon present in all its allotropes burn in sufficient amount of oxygen. On burning it produces carbon dioxide and water and liberate heat and light. These reaction are oxidation reactions.

Oxidation:
Oxidation is the reaction in which carbon compounds take up oxygen in the presence of oxidizing agents to give another compound.

Addition (Hydrogenation) reaction:
A reaction in which adding one molecule to an organic compound gives a new but single organic compound is called addition reaction.

Substitution reaction:
A reaction in which one or more hydrogen atoms of a hydrocarbon are substituted (replaced) by some other atom(s) (such as chlorine) is called a substitution reaction.

Some Important Carbon Compounds – Ethanol and Ethanoic Acid

Ethanol:

• Ethanol is the second member of the homologous series of alcohol. Its formula is C₂H₅OH.
• Ethanol or ethyl alcohol is the most common and most widely used alcohol and hence is also simply called alcohol.

Ethanoic acid:

• Ethanoic acid is the second member of the homologous series of carboxylic acids.
• Its formula is CH₂COOH. The common name of ethanoic acid is acetic acid.

Soaps and Determents

Soap:

• A molecule of soap is a sodium or potassium salt of long chain carboxylic acid.
• Each long chain soap molecule is made up of two parts. They are: (1) a polar head and (2) a polar tail.

Detergents:

• Detergent is a chemical substance used for cleaning purposes.
• A molecule of detergent is ammonium or sulphonate salt of long chain carboxylic acid.
• In detergent, the functional group sodium sulphonate (-SO₃Na) is attached to the long chain of hydrocarbon.