Question

How does electronegativity affect the type of bond?

Answer 1

The electronegativity is the measure of the ability or the tendency of an atom to attract the shared pair of electrons towards itself. It is a relative measure and depends on the ability of the adjacent molecule too. Variation in extent of electronegativity gives rise to different types of bonds.

Complete step-by-step answer:
The term electronegativity can be defined as the measure of the ability of an element to attract the shared pair of electrons which is involved in bonding, towards its own self. Electronegativity of an atom is not absolute or fixed, meaning, it depends on the ability of the other atom too, with which it is bonded.

For an instance if atom $1$ has higher value of electronegativity than atom $2$, then it is not necessary it has absolute higher value, it could have lower electronegativity value than atom $3$. Which means it's just a relative measure of the ability. The bonds formed between these atoms $1$ and $2$ is called a polar bond, because the shared pair of electrons will be slightly shifted towards the atom $2$. For instance, the bond between hydrogen and oxygen in water.

If in case the electronegativity of both the bonds turned out to be equal, then the bond which is formed as a result, would be termed as a covalent bond. For instance, the bond formed between carbon and hydrogen in methane.

In case the electronegativity difference is too high, then the atom with the higher electronegativity will take both the electrons and form a negative charge, while the other atom will eventually form positive charge, and so the bond would become an ionic bond. For instance, the bond between sodium and chloride in sodium chloride.

Note:
i) The variation of electronegativity, or the extent of electronegativity can result in formation of different types of bonds.
ii) If the electronegativity difference between two atoms is moderate, then the bond formed between the two atoms would be a polar bond. If the electronegativity is the same, in both the atoms, then it would result in the formation of covalent bonds.
iii) And if the electronegativity difference is too high, then it would form an ionic bond