Question

How do polar bonds contribute to polarity of a molecule?

Answer 1

Hint:Polarity is defined as a condition of molecules having positive and negative charges especially in the case of electrical poles and magnetic poles. The polarity of bond can be seen between the molecules having various electronegativities.

Complete step-by-step answer:Polarity is defined as the separation of electric charges that results in the formation of positive and negative ends in a molecule. In the case of \[H-F\] bond, the fluorine is more electronegative than hydrogen and hence has more electrons on fluorine than hydrogen atom. Therefore fluorine atom slightly becomes negative and hydrogen atom slightly becomes positive.
Let us take an example of $H-F$ . If a molecule has one polar bond that means it will have one positive charge on one end and one negative charge on the other end. That molecule is known as polar.
But if a molecule has more than one polar bond then the polarity of a molecule depends upon the arrangement of the bonds. If a polar bond is arranged symmetrically then the dipoles of the bond cancel out and do not make a molecular dipole.
Let us take an example of $B{{F}_{3}}$ , the bonds in this molecule is polar but they point at angle of ${{120}^{{}^\circ }}$ around the central boron atom. The centre of three negative charges is on boron atom and the centre of one positive charge is also on boron atom. The positive and negative charges coincide and hence there is no dipole moment and the molecule is considered to be non polar.

Note:In this question we have talked about the polar molecules which contain slightly positive charge in one end and slightly negative charge in another end. The molecule that does not have charges is known as non polar molecules. The polarity of the molecule depends upon the arrangement of the bonds.