Explain why carbon forms compounds mainly by covalent bond. Explain in brief two main reasons for carbon forming a large number of compounds. Why does carbon form strong bonds with most other elements?

Hint: Due to the number of electrons present in the last shell, carbon forms covalent compounds. The two main reasons are tetravalency and catenation among carbon to form large compounds.

Complete step by step answer:
Covalent bonds are formed by the overlapping of atomic orbitals in a particular direction. They are directional in nature. Carbon belongs to group 14. Its atomic number is 6 and has 4 valence electrons in its valence shell. It is not easy to lose all four electrons because a lot of energy will require and hence it cannot lose all the electrons in order to gain stability. It is also not possible to gain all four electrons because it will create so much repulsion. The only option left with carbon is to share its electrons with others in order to complete its octet and hence it forms covalent bonds.

The reasons for the formation of large number of compounds are:
1. Tetravalency: As carbon has 4 electrons in its valence shell and hence can share these electrons with other elements to form large numbers of compounds. It can share its 4 electrons with different atoms or molecules thus generating enormous compounds.
2. Catenation: Catenation is the property of self linking that is the ability of an atom to link to itself. Carbon forms strong bonds with another carbon due to the overlapping of orbitals. This leads to the large number of organic compounds.

Due to the small size of carbon the nucleus holds the lone pair of electrons tightly. The overlapping form is strong and hence the carbon compounds generally have strong bonds.

Note:
The second member of the carbon family is silicon. Up to some extent silicon also shows catenation and forms self linking compounds but the extent of overlapping is not that great as in case of carbon.