i. How is covalent bond formed between two atoms?
ii. Consider two covalently bonded atoms Q and R where R is more electronegative than Q.
Will these atoms share the electron pair equally between them?
iii. Represent the above polar covalent bond between Q and R using fractional charges δ+ and δ-.
i. A covalent bond is formed between two atoms by mutual sharing of electrons so as to complete their octets or duplets (in case of elements having only one shell).
ii. A covalent bond is formed between Q and R having different electronegativities, that is, R is more electronegative than Q.
In such a case,
The atom R with a higher value of electronegativity pulls the shared pair of electrons to a greater extent towards itself as compared to the atom Q with lower value of electronegativity.
As a result of this,
The shared pair of electrons will get shifted towards atom R.
Thus,
Both the atoms Q and R will not share the electron pair equally between them.
iii. Polar covalent bond between Q and R can be represented as :
\(Q^{δ+}-R^{δ-}\)