Now that you know how crucial carbon is for human survival on our planet, let’s look at the features of carbon compounds.

• They are poor conductors of electricity
• Low Melting point and Boiling point gives us the conclusion that the force of attraction between the molecules is weak

As you all know, the atomic number of carbon is 6. The outermost shell of carbon has four electrons. To attain noble gas configuration, carbon has to gain or lose four electrons from its outermost shell. But this is not an easy task for carbon. If it gains four electrons becoming a C^4- anion, the nucleus with six protons has to hold ten electrons. On the other hand, if it loses four-electron to form a C⁴⁺ cation, the nucleus with six protons will hold on to two electrons. Carbon overcomes this difficulty by sharing its valence electron with other carbon atoms or atoms from other elements. 

Such bonds exist in some simple molecules like H₂, O_2, and N₂. The atomic number of hydrogen is 1. The K shell has one electron. A molecule of hydrogen, H₂ is formed when two hydrogen atoms share their electrons, thus attaining noble gas configuration. The valence electrons are represented using dots or crosses. The single covalent bond between the hydrogen atoms is represented by a line between them. Fig.

Now we will see a carbon compound that is used as fuel -Methane. It has a formula of CH₄. Carbon has four valence electrons and hydrogen has one valence electron. So, to achieve the noble gas configuration carbon shares its 4 electrons with four atoms of hydrogen. Fig.

The bonding in carbon is Covalent.  A covalent bond is a chemical bond in which the electrons of the atoms are shared equally. Here the electrons in the outermost shell are shared. Such molecules have strong bonds within the molecule, but the intermolecular forces are weak. This is the reason for the low boiling and melting point of such compounds. These covalent compounds are poor conductors of electricity as the electrons are shared between atoms and no charged particle is formed.

 Versatile Nature of Carbon

1. Catenation

Carbon can form bonds with other atoms of carbon, which give rise to large molecules. This property of carbon is called catenation. Such compounds have long chains of carbon, branched chains of carbon or carbon atoms arranged in rings. Carbon atoms may also be linked through single, double, or triple bonds. Carbon compounds linked by single bonds are called saturated compounds. Those carbon compounds which are linked through double or triple bonds are called unsaturated compounds.

2. Tetravalency

Carbon has a valency of four and can bond with four other carbon atoms or atoms of other mono-valent elements. Carbon forms a compound with hydrogen, oxygen, nitrogen, sulphur, chlorine, and many other elements. These bonds are very strong making the compounds stable.

 Saturated and Unsaturated Carbon Compounds

To make the structure of saturated or unsaturated carbon compounds, the first step is to link the carbon atoms with a single bond and then satisfy the remaining valencies of carbon using hydrogen atoms.

Let’s see the steps to arrive at the structure of ethane (C₂H₆)

Step 1-Carbon atoms are linked together with a single bond

Step 2-Each carbon atom is bonded to three hydrogen atoms to complete the carbon’s valency of four.

Fig- Electron dot structure of ethane

In compounds like methane, ethane, and propane the valencies of all atoms are satisfied by single bonds between them. These carbon compounds are called saturated compounds. They are normally not reactive.

Let’s see the steps to arrive at the structure of ethene(C₂H₄)

Step 1-  carbon and carbon can be linked through a single bond.

Step-2- Each carbon atom is attached to two hydrogen atoms.

Step-3-Even after step 2 the valency of the carbon atom is not satisfied(valency-4), to satisfy the valency we need a double between the two carbon atoms.

Fig- Electron dot structure of Ethene

Thus some compounds are formed using double or triple bonds between the carbon atoms. Such compounds are called unsaturated compounds. They are more reactive than saturated carbon compounds. Eg Ethene(C₂H₄) and ethyne (C₂H₂).

Chains, Branches, and Rings

Carbon compounds like methane, ethane, and propane contain 1,2 and 3 carbon atoms respectively. Such chains of the carbon atom can contain many more carbon atoms. Let’s look at some of these carbon chains.