Carbon and Its Compounds

Versatile Nature of Carbon

Carbon has two unique properties, i.e. tetravalency and catenation. Because of these properties carbon forms a large number of compounds. There are more than three million compounds of carbon known so far.

Catenation

The linkage of atoms of same elements to form longer chain is called the CATENATION.

Carbon has unique property to form bonds with other atoms of carbon forming a long chain. Because of the property of catenation, carbon forms straight chain, branched chain, cyclic rings. In addition to this carbon atoms can be linked by single, double or triple bonds.

Tetravalency of Carbon

Carbon has four electrons in its outermost orbit. This means carbon has four valence electrons. Because of this carbon is called tetravalent.

Because of four valency, carbon can form bond with four other carbon atoms or atoms of other monovalent elements.

Carbon forms covalent bonds, which are very strong. On the other hand atom of carbon has small size this makes compounds of carbon exceptionally stable.

Hydrocarbon

Hydrogen + Carbon = Hydrocarbon

Chemical compounds form entirely by the combination of only carbon and hydrogen are called hydrocarbons.

Hydrocarbons are of two types: Saturated hydrocarbons and Unsaturated hydrocarbons.

Saturated and Unsaturated Carbon Compounds

Saturated Carbon Compounds

Carbon compounds that have chain of carbon atoms linked together with single covalent bonds are called SATURATED CARBON COMPOUNDS.

Example: Methane (CH₄), Ethane (C₂H₆), chloromethane (CH₃Cl), etc.

Saturated hydrocarbons are known as Alkanes.

General formula of Alkane: C_nH_{2n + 2}

Where, n = number of carbon atoms

(1) If n = 1

∴ C_nH_{2n + 2}

= C₁H_{2 x 1 + 2} = CH₄

Saturated Hydrocarbon having one carbon atom is called METHANE

(2) If n = 2

∴ C_nH_{2n + 2}

= C₂H_{2 x 2 + 2} = C₂H₆

Saturated Hydrocarbon having two carbon atoms is called ETHANE

(3) If n = 3

∴ C_nH_{2n + 2}

= C₃H_{2 x 3 + 2} = C₃H₈

Saturated Hydrocarbon having two carbon atoms is called PROPANE

(4) If n = 4

∴ C_nH_{2n + 2}

= C₄H_{2 x 4 + 2} = C₄H₁₀

Saturated Hydrocarbon having two carbon atoms is called BUTANE

Here, the prefix 'buta' means four. Thus, this compound is named as Butane.

In the name of this caompound, 'Buta' means four and 'ane' exists for alkane.

(5) If n = 5

∴ C_nH_{2n + 2}

= C₅H_{2 x 5 + 2} = C₅H₁₂

Saturated Hydrocarbon having two carbon atoms is called PENTANE

Here, prefix 'penta' means five, therefore, this saturated hydrocarbon having five carbon atoms is known as Pentane.

(6) If n = 6

∴ C_nH_{2n + 2}

= C₆H_{2 x 6 + 2} = C₆H₁₄

Saturated Hydrocarbon having two carbon atoms is called HEXANE.

Here, prefix 'hexa' means six, therefore, this saturated hydrocarbon having six carbon atoms is known as Hexane.

(7) If n = 7

∴ C_nH_{2n + 2}

= C₇H_{2 x 7 + 2} = C₇H₁₆

Saturated Hydrocarbon having two carbon atoms is called HEPTANE.

Here, prefix 'hepa' means seven, therefore, this saturated hydrocarbon having seven carbon atoms is known as Heptane.

(8) If n = 8

∴ C_nH_{2n + 2}

= C₈H_{2 x 8 + 2} = C₈H₁₈

Saturated Hydrocarbon having two carbon atoms is called Octane.

Here, prefix 'octa' means eight, therefore, this saturated hydrocarbon having seven carbon atoms is known as Octane.

[This is similar to the word 'Octopus'. Octopus is a sea animal. Here 'Octa' means eight and 'pus' means foot ['pus' came from Greek word 'pous' which means foot]. This means animal with eight feet.

(9) If n = 9

∴ C_nH_{2n + 2}

= C₉H_{2 x 9 + 2} = C₉H₂₀

Saturated Hydrocarbon having two carbon atoms is called Nonane.

Here, prefix 'nona' means nine, therefore, this saturated hydrocarbon having seven carbon atoms is known as Nonane.

(10) If n = 10

∴ C_nH_{2n + 2}

= C₁₀H_{2 x 10 + 2} = C₁₀H₂₂

Saturated Hydrocarbon having two carbon atoms is called Decane.

Here, prefix 'deca' means ten, therefore, this saturated hydrocarbon having seven carbon atoms is known as Decane.

Apart from these there are many other saturated hydrocarbons.

Unsaturated Carbon Compounds

Hydrocarbons with double or triple bonds are called Unsaturated Hydrocarbons or Unsaturated Carbon compounds.

Example: Ethylene (C₂H₄), Acetylene (C₂H₂), etc.

Unsaturated Hydrocarbons can be further divided into two types: Hydrocarbons with double bonds and Hydrocarbons with triple bonds.

Alkene: Hydrocarbons with Double Bonds

Hydrocarbons with double bonds are called ALKENE.

Alkane – ane + ene = Alkene

General Formula of Alkene = C_nH_2n

(1) If n = 1

∴ C_nH_2n

= C₁ H _{2 x 1} = CH₂

This compound does not exist.

(2) If n = 2

∴ C_nH_2n

= C₂ H _{2 x 2} = C₂H₄

This compound is known as Ethene

[Ethane – ane + ene = Ethene]

(3) If n = 3

∴ C_nH_2n

= C₃ H _{2 x 3} = C₃H₆

This compound is known as Propene

[Propane – ane + ene = Propene]

(4) If n = 4

∴ C_nH_2n

= C₄ H _{2 x 4} = C₄H₈

This compound is known as Butene

[Butane – ane + ene = Butene]

In this hydrocarbon, the prefix 'buta' indicates the presence of four carbon atoms.

Unsaturated Hydrocarbons with triple bond

Unsaturated hydrocarbon with triple bond is called Alkyne.

Alkane – ane + yne = Alkyne

General Formula of Alkyne = C_nH_2n–2

(1) If n = 1

∴ C_nH_2n–2

= C₁ H _{2 x 1–2} = CH₀

This compound does not exist.

(2) If n = 2

∴ C_nH_2n–2

= C₂ H _{2 x 2–2} = C₂H₂

This unsaturated hydrocarbon is called Ethyne [Ethane – ane + yne = Ethyne]

(3) If n = 3

∴ C_nH_2n–2

= C₃ H _{2 x 3–2} = C₂H₄

This unsaturated hydrocarbon is called Propyne [Propane – ane + yne = Propyne]

(4) If n = 4

∴ C_nH_2n–2

= C₄ H _{2 x 4–2} = C₄H₆

This unsaturated hydrocarbon is called Butyne [Butane – ane + yne = Butyne]