Question

How many sigma bonds and pi bonds are in ${{O}_{3}}$?

Answer 1

Hint: Sigma bonds are formed where there is a single bond. While pi bonds are formed where there are double or triple bonds. Sigma bonds are the basis for pi bonds. Sigma bonds are a result of end to end overlapping, while pi bonds are formed by sideways overlapping.

Complete answer: We have been asked to give the number of sigma and pi bonds in the ozone, ${{O}_{3}}$ molecule. As we know sigma bonds consist of only one electron cloud and for single bonds, while pi bonds have two electron clouds and are the bonds in double or triple bonds.
The number of sigma and pi bonds is identified by the recognition of double and single bonds. One single bond represent 1 $\sigma $, sigma bond; while where there is one double bond, it means that 1 $\sigma $, sigma bond is involved along with 1$\pi $, pi bond, as without forming a sigma bond, a pi bond will not be formed.
Now, for the number of sigma bonds and pi bonds in ozone, we will see its resonating Lewis structure representation as:
$O={{\overset{\bullet \bullet }{\mathop{O}}\,}^{+}}-{{O}^{-}}$
This structure clearly shows that the number of valence electrons that form bonds with the oxygen atom are 6, 5,7 on oxygen atoms from left to right respectively. As, we can see one single bond, this shows the presence of 1 $\sigma $bond. On the other hand, we can see one double bond that shows the presence of 1 $\sigma $bond and 1$\pi $bond. So, the total sigma bonds are 2 and pi bonds are 1.
Hence, in the molecule of ${{O}_{3}}$, total 2$\sigma $, sigma bonds are present and 1$\pi $, pi bond is present.

Note: In sigma bonds, the overlapping of atomic orbitals is end to end along the internuclear axis, while in pi bonds it is sideways, hence, one electron cloud in sigma bond, and two electron clouds in pi bonds, one above and one below.