Revision: Carbon and its Compounds Science English Medium Class 10 CBSE

The molecule formed due to the sharing of electrons (covalent bond) is called a covalent molecule.

The chemical bond that is formed between two combining atoms by mutual sharing of one or more pairs of electrons is called a covalent (or a molecular) bond, and the compound formed due to this bond is called a covalent compound.

The bond formed between two atoms by sharing a pair of electrons, provided entirely by one of the combining atoms but shared by both, is called a coordinate bond. 

The chemical bond formed between two combining atoms by mutual sharing of one or more pairs of electrons is called a covalent bond.

When an element possess 2 or more different forms in the same state, they are called allotropes and the phenomenon is known as allotropy. Diamond and graphite are the 2 allotropes of carbon.

Adsorption is the property due to which a substance absorbs gases, liquids and solids on its surface.

The process of the slow conversion of vegetable matter into carbon-rich substances is called carbonization.

Carbon possesses a unique property of combining with other carbon atoms to form long chains. This property is called catenation. The chains can be straight, branched or closed.

The self-linking property of atoms of an element to form very long straight or branched chains and cyclic rings is known as catenation. This property is shown by carbon whose small size and tetravalency helps it to form large structures by self-linking.

The characteristic of the carbon atom, by virtue of which it forms four covalent bonds, is called the tetravalency of carbon.

The property of self-linking of atoms of an element through covalent bonds in order to form straight chains, branched chains and cyclic chains of different sizes is known as catenation.

Organic compounds are the compounds of carbon.

When two or more compounds have a similar molecular formula but are different in the arrangement of carbon atoms in straight or branched chains, the compounds are referred to as chain isomers.

Compounds having the same molecular formula but different structural formulas are called isomers and the phenomenon is called isomerism.

An atom or a group of atoms attached to an alkyl group, which takes part in most of the chemical reactions, is called a functional group or functional radical.

The compounds of carbon having double or triple bonds between the carbon atoms are known as unsaturated carbon compounds.

The valencies of all the atoms are satisfied by single bonds between them. Such carbon compounds are called saturated compounds.

The heteroatoms and the group containing these confer specific properties to the compound, regardless of the length and nature of the carbon chain and hence are called functional groups.

The saturated hydrocarbons are called alkanes.

The unsaturated hydrocarbons which contain one or more double bonds are called alkenes.

Those containing one or more triple bonds are called alkynes.

Compounds with identical molecular formula but different structures are called structural isomers.

The carbon compounds which contain only carbon and hydrogen are called hydrocarbons.

A series of compounds with similar chemical properties, in which members differ from one another by an additional CH₂ group, is called a homologous series.

The same functional group substitutes for hydrogen in a carbon chain is called a homologous series.

OR

A homologous series is a group of organic compounds having  similar structure and similar chemical properties in which the successive compounds differ by a CH₂ group.

OR

The series of compounds formed by joining the same functional group in the place of a particular hydrogen atom on the chains having sequentially increasing length is called homologous series.

Nomenclature is the system of assignment of names to organic compounds.

C_nH_2n+1COOH (or RCOOH)

• Carbon forms covalent bonds by sharing electrons to achieve a noble gas configuration.
• Covalent bonds can be single, double, or triple, as seen in molecules like H₂, O₂, and N₂.
• Covalent compounds have low melting and boiling points and are poor conductors of electricity.
• Carbon has allotropes such as diamond, graphite, and fullerene (C₆₀), each with different physical properties.

• The IUPAC system provides a unique, systematic way to name carbon compounds based on structure, replacing confusing common names.
• An IUPAC name has three parts: prefix, parent, and suffix, reflecting the carbon chain and functional group.
• The parent name is based on the longest carbon chain, and its ending changes to –ane, –ene, or –yne depending on the number of bonds.
• Functional groups are shown as prefixes or suffixes, and the chain is numbered to give them the lowest possible number.
• If the suffix begins with a vowel, the final ‘e’ in the parent alkane name is dropped (e.g., propane → propanone).

• Ethanol is a colourless liquid with a boiling point of 78 °C, soluble in water, and used in medicines, drinks, and as a clean-burning fuel (e.g., gasohol).
• Ethanol reacts with sodium to form sodium ethoxide and hydrogen gas is evolved.
• When heated with concentrated H₂SO₄ at 170 °C, ethanol undergoes dehydration to form ethene, an unsaturated compound.
• Methanol is highly poisonous, and industrial ethanol is made unfit for drinking by mixing methanol and adding a blue dye (denatured spirit).

• Ethanoic acid (acetic acid) is a carboxylic acid; its 5–8% aqueous solution is vinegar, and it shows acidic nature by turning blue litmus red.
• Pure ethanoic acid freezes at 17 °C (290 K), so it is called glacial acetic acid.
• Being a weak acid, ethanoic acid is not completely ionised in aqueous solution.
• Ethanoic acid reacts with bases, carbonates, and bicarbonates to form a salt, water, and CO₂ (CO₂ turns lime water milky).
• It reacts with ethanol in the presence of conc. H₂SO₄ to form an ester (ethyl ethanoate) with a sweet smell (esterification).