Revision: Carbon Compounds Science and Technology 1 SSC (English Medium) 10th Standard Maharashtra State Board

All the compounds having carbon as a constituent element are called as organic compounds.

The chemical bond formed by sharing of two valence electrons between the two atoms is called covalent bond.

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

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.

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

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.

Saturated hydrocarbons are hydrocarbons in which the valencies of all atoms are satisfied by single bonds.

The hydrocarbons that have double or triple covalent bonds between two adjacent carbon atoms are called unsaturated hydrocarbons.

OR

The carbon compounds having a double bond or triple bond between two carbon atoms are called unsaturated compounds. Ethene and ethyne are unsaturated hydrocarbons.

The unsaturated hydrocarbons whose structures contain a carbon-carbon triple bond are called ‘Alkynes’.

Saturated hydrocarbons (containing a single bond) are called ‘Alkanes’.

Hydrocarbons are compounds that 9re made up only of carbon and hydrogen atoms.

OR

The compounds which contain carbon and hydrogen as the only two elements are called hydrocarbons.

The unsaturated hydrocarbons containing a carbon-carbon double bond are called ‘Alkenes’.

The compounds having this characteristic unit in their structure are called aromatic compounds.

The compounds which contain carbon and hydrogen as the only two elements are called hydrocarbons.

"The hetero atoms or the groups of atoms containing hetero atoms are called functional groups."

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.

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.

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

Redox reactions are those in which reduction and oxidation both takes place simultaneously i.e. one substance is reduced while the other gets oxidised.

Chemical substances which bring about an oxidation reaction by making oxygen available are called oxidants or oxidizing agents.

OR

Substances that can give oxygen to other substances are called oxidants or oxidizing agents.

The chemical reaction in which a reactant combines with oxygen or loses hydrogen to form the product is called oxidation reaction.

Those reactions in which hydrogen combines with a substance or oxygen is removed from a substance, are known as reduction reactions.

Example: \[\ce{2HgO->[heat]2Hg +O2}\]

When the surface of a metal is attacked by air, moisture or any other substance around it, the metal is said to corrode and the phenomenon is known as corrosion.

Corrosion is an electrochemical process in which a metal is oxidised to a metal oxide or another salt of the metal by losing electrons to oxygen or another electronegative element, forming a coating on the metal surface.

The chemical reaction in which reactants gain oxygen to form the corresponding oxide. Also, A chemical reaction in which reactants lose hydrogen to form a product is called oxidation.

Example: \[\ce{H2S + Cl -> 2HCl + S}\]

The oxidation number of an element is defined as the formal charge that an atom of that element appears to have when electrons are counted.

The reaction in which the place of one type of atom/group in a reactant is taken by another atom/group of atoms is called a substitution reaction.

• \[\mathrm{CH}_4+\mathrm{Cl}_2\xrightarrow{\mathrm{Sunlight}}\mathrm{CH}_3-\mathrm{Cl}+\mathrm{HCl}\]
  → 1 hydrogen replaced → methyl chloride
• \[\mathrm{CH}_3\mathrm{Cl}+\mathrm{Cl}_2\xrightarrow{\mathrm{Sunlight}}\mathrm{CH}_2\mathrm{Cl}_2+\mathrm{HCl}\]
  → 2 hydrogens replaced → methylene chloride
• \[\mathrm{CH}_2\mathrm{Cl}_2+\mathrm{Cl}_2\xrightarrow{\mathrm{Sunlight}}\mathrm{CHCl}_3+\mathrm{HCl}\]
  → 3 hydrogens replaced → chloroform
• \[\mathrm{CHCl}_3+\mathrm{Cl}_2\xrightarrow{\mathrm{Sunlight}}\mathrm{CCl}_4+\mathrm{HCl}\]
  → All 4 hydrogens replaced → carbon tetrachloride

• Organic compounds are mainly carbon compounds, except CO₂, CO, carbonates, bicarbonates, and carbides, which are inorganic.
• Carbon compounds have low melting and boiling points (generally below 300 °C) due to weak intermolecular forces.
• Most carbon compounds do not conduct electricity, showing the absence of ionic bonds.
• Carbon forms covalent bonds by sharing electrons to achieve a stable noble gas configuration.
• Carbon can form single, double, and triple covalent bonds, allowing the formation of many compounds like CH₄, O₂, and N₂.

• Hydrocarbons contain only carbon and hydrogen atoms and are the basic type of organic compounds.
• Saturated hydrocarbons have single bonds (e.g. methane, ethane, propane).
• Unsaturated hydrocarbons have double or triple bonds (e.g. ethene, ethyne).
• To draw structures, join the carbon atoms first, then add hydrogen atoms to complete 4 bonds per carbon.
• Ethene has a double bond, and ethyne has a triple bond between carbon atoms.

• Carbon compounds can have straight, branched, or ring chains of carbon atoms.
• Isomers have the same formula but different structures (e.g., butane).
• Crude oil is a mix of hydrocarbons; fuels like LPG and petrol are separated by fractional distillation.
• Saturated hydrocarbons have single bonds, while unsaturated ones have double or triple bonds.
• Aromatic compounds, such as benzene, have rings with alternating double bonds.

• 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).

• Unsaturated compounds undergo addition reactions with hydrogen in the presence of a nickel or platinum catalyst to form saturated compounds.
• Hydrogenation of vegetable oils with a nickel catalyst converts unsaturated fats into saturated fats, such as Vanaspati ghee.
• Unsaturated fats with double bonds are healthier, whereas saturated fats are considered harmful to health.

• 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).

• Macromolecules are large molecules made of many atoms; they include natural and manmade polymers.
• Natural macromolecules like starch, cellulose, proteins, and DNA are essential for life.
• Man-made macromolecules such as plastics, fibres, and rubber are used in daily life.
• Polymers are made by repeating small units called monomers through polymerization.
• Properties of polymers depend on the type of monomers and how they are arranged (straight, branched, or cross-linked).