Carbon and its compounds

Carbon: Introduction

Atomic Number: 6
Electronic configuration: 2, 4
Valence electrons: 4
Property: Non-metal

Abundance: Carbon is the 4th most abundant substance in universe and 15th most abundant substance in the earth’s crust.

Compounds having carbon atoms among the components are known as carbon compounds. Previously, carbon compounds could only be obtained from a living source; hence they are also known as organic compounds.

Bond formed by sharing of electrons is called covalent bond. Two of more atoms share electrons to make their configuration stable. In this type of bond, all the atoms have similar rights over shared electrons. Compounds which are formed because of covalent bond are called COVALNET COMPOUNDS.

Covalent bonds are of three types: Single, double and triple covalent bond.

Single Covalent Bond: Single covalent bond is formed because of sharing of two electrons, one from each of the two atoms.

Formation of hydrogen molecule (H₂)

Atomic Number of H = 1
Electronic configuration of H = 1
Valence electron of H = 1

Hydrogen forms a duet, to obtain stable configuration. This configuration is similar to helium (a noble gas).

Since, hydrogen has one electron in its valence shell, so it requires one more electron to form a duet. So, in the formation of hydrogen molecule; one electron from each of the hydrogen atoms is shared.

Formation of hydrogen chloride (HCl):

Valence electron of hydrogen = 1
Atomic number of chlorine = 17
Electronic configuration of chlorine: 2, 8, 7
Electrons in outermost orbit = 7
Valence electron = 7

Formation of chlorine molecule (Cl₂):

Valence electron of chlorine = 7

Formation of water (H₂O)

Valence electron of hydrogen = 1
Atomic number of oxygen = 8
Electronic configuration of oxygen = 2, 6
Valence electron = 6

Oxygen in water molecule completes stable configuration by the sharing one electron from each of the two hydrogen atoms.

Formation of Methane (CH₄)

Valence electron of carbon = 4
Valence electron of hydrogen = 1

Formation of Ethane (C₂H₆):

Double covalent bond: Double bond is formed by sharing of four electrons, two from each of the two atoms.

Formation of oxygen molecule (O₂):

Valence electron of oxygen = 2

In the formation of oxygen molecule, two electrons are shared by each of the two oxygen atoms to complete their stable configuration.

In oxygen, the total number of shared electrons is four, two from each of the oxygen atoms. So a double covalent bond is formed.

Formation of Carbon dioxide (CO₂):

Valence electron of carbon = 4
Valence electron of oxygen = 6

In carbon dioxide two double covalent bonds are formed.

Formation of Ethylene (C₂H₄):

Valence electron of carbon = 4
Valence electron of hydrogen = 1

Triple Covalent Bond: Triple covalent bond is formed because of the sharing of six electrons, three from each of the two atoms.

Formation of Nitrogen (N₂):

Atomic number of nitrogen = 7
Electronic configuration of nitrogen = 2, 5
Valence electron = 5

In the formation of nitrogen, three electrons are shared by each of the nitrogen atoms. Thus one triple bond is formed because of the sharing of total six electrons.

Formation of Acetylene (C₂H₂):

Properties of Covalent Bond:

• Intermolecular force is smaller.
• Covalent bonds are weaker than ionic bond. As a result, covalent compounds have low melting and boiling points.
• Covalent compounds are poor conductor of electricity as no charged particles are formed in covalent bond.
• Since, carbon compounds are formed by the formation of covalent bond, so carbon compounds generally have low melting and boiling points and are poor conductor of electricity.