Question

How does a polar covalent bond differ from a nonpolar covalent bond?

Answer 1

A bond which is formed between atoms of different electronegativity. Difference in electronegativity tells us which part of the bond will attract the shared electron pair. Compounds having this type of attraction of shared electrons towards one atom and not in between of that bond have polarity while others don’t have it.

Complete step by step answer:
Firstly we will see that what is a covalent bond? A bond which is formed by sharing of electrons is called a covalent bond. We know that in the periodic table there are elements on the right hand side of the table which have higher electronegativity while on the left hand side, there are less electronegativity. Electronegativity is a term used for the attraction of nucleus on its outermost electrons. This concept of electronegativity gives us ideas about a polar and a nonpolar bond.
A polar bond is generally formed between the atoms of different electronegativity like for example, consider hydrogen fluoride, in this molecule hydrogen is less electronegative in nature while fluorine is more electronegative. Therefore the bond present between them is of course a covalent bond but it is called a polar covalent bond, we add polar word because of the electronegativity difference between them. Another example is of hydrogen chloride gas $HCl$ fumes that we learn are of white colour, here also there is a bond form between hydrogen and chlorine that is why we can call it a polar covalent compound.
${H^{\partial + }} - {F^{\partial - }}$
${H^{\partial + }} - C{l^{\partial - }}$
A nonpolar bond is as the name suggests not having a polarity. A bond formed between the atoms of same electronegativity, for example oxygen molecule ${O_2}$ . In an oxygen molecule, two atoms of oxygen combine by sharing electrons and form a double bond between them, this double bond is due to the sharing of two electron pairs by each oxygen. As we see above when a bond is formed between two same atoms it is called a nonpolar covalent bond. There are many examples that we can recall of polar and nonpolar covalent bonds.
$O = O$
As we know, the air that we breathe has nitrogen gas ${N_2}$ in it. Nitrogen gas is formed by two atoms of nitrogen atoms, no electronegativity difference hence it also includes a nonpolar covalent bond.

Note: Polarity and non polarity is mainly a concept of electronegativity so the elements which are on the right hand side of the periodic table that is of p block are more electronegative and elements on the left hand side are less electronegative. This trend of electronegativity increases as we go from left to right.