Question

How many single covalent bonds can a carbon atom form?

Answer 1

Covalent bond is a type of chemical bond which is formed by the sharing of electrons between the bonded atoms. The bonded atoms have similar electronegativity.

Complete step by step answer:
Covalent bond between two atoms is the result of bonding caused by the sharing of electron pairs. The atoms bonded are close in electronegativity. Due to less electronegativity difference the electron density of the bond resides in the middle of the bonded atoms.
If the electronegativity difference is more between the bonded atoms then the bond becomes ionic in nature. In that case, the electron density of the bond moves towards the more electronegative atom.
Carbon is an atom in the periodic table with atomic number $6$ and electron configuration $\left[ {He} \right]2{s^2}2{p^2}$ . The outermost shell of carbon is $2$ with a total of four valence electrons. Of the four valence electrons, two electrons are present in the $2s$ orbital and two in the $2p$ orbital in the ground state of the carbon atom.
In the excited state one of the electrons from the $2s$ orbital enters into the $2p$ orbital. Thus all the three $2p$ orbitals of carbon are singly filled along with an electron in the $2s$ orbital. As a result four electrons are available for bonding with other atoms and so it shows a valency of four to complete the octet.
Hence, the four electrons in carbon are able to make four single covalent bonds with other atoms.

Note:
The carbon atoms have the ability to form bonds with itself. This property leads to the formation of graphite and diamond. Here also the carbon atom forms four single covalent bonds with the nearby carbon atom.