Question

What is the definition of covalent bond?

Answer 1

To understand covalent compounds, we need to understand the concept of covalent bond formation. This type of bonding takes place between elements with minimal difference in electronegativity values that involves approximately equal sharing of electrons between two elements.

Complete answer:
All elements in the universe try to achieve a stable state configuration. Chemical species also attain stability by forming favorable bonds with each other. It could be an ionic or a covalent bond. Based on the type of bonds formed in a compound, inorganic compounds are classified as ionic and covalent compounds. It further depends upon the electronegativity of the participating elements.
Electronegativity is the tendency of an atom to attract electrons towards itself in a chemical bond. Elements with a large difference in electronegativity values tend to form ionic bonds and elements having similar electronegativity tend to form covalent bonds.
When the reacting elements do not differ much in electronegativity, then they tend to share electrons equally among themselves. This sharing of electrons results in the formation of a covalent bond. And the compound formed is known as the covalent compound.
Usually, covalent bonds form between a metal and a nonmetal. Some examples of covalent compounds are ${{\text{H}}_{\text{2}}}\text{O}$, $\text{C}{{\text{O}}_{2}}$ etc.
Hence, covalent bond is the bond formed when the equal sharing of bonding pairs of electrons takes place among its constituent atoms.

Note:
There is a limitation in covalent bonding. The covalent compounds do not always show pure covalent bonding. Sometimes, when electronegativity difference is not very similar and one atom attracts the bonding electrons slightly more than the other, asymmetrical distribution of electrons takes place making one end of the molecule more electron-rich and the other end electron-deficient. This results in the formation of a polar molecule.