Question

Write resonance structure for ${\mathrm{SO}}_2$and ${\mathrm{CO}}_2$?

Answer 1

Resonance structure for ${\mathrm{SO}}_2$:

1. Resonating structure is defined as two or more possible structures having identical geometry but different arrangements of paired electrons, this phenomenon is known as ‘resonance’
2. Sulfur dioxide $\left({\mathrm{SO}}_2\right)$ has two resonating structures which contribute to a hybrid structure
3. Steps of Drawing resonating structure of ${\mathrm{SO}}_2$

• Sulfur has '$4$‘ valence electrons and each Oxygen has ’$6$' valence electrons.
• Total number of valence electrons=$4+2\left(6\right)$=$18$

• From the above figure it depicts the $6$ bonding electrons and non-bonding electrons in them$12$.
• As both structures are equivalent so both of them contribute to the hybrid structure${\mathrm{SO}}_2$.
• As Oxygen is more electronegative than Sulfur so the negative charge is placed on Oxygen
• So, the hybrid structure ${\mathrm{SO}}_2$will be:

• The negative charge will be split among two Oxygen atoms.
• The charge on Sulfur is $+1.4$
• The charge on Oxygen is$-0.7$
• The molecule has a single bond as well as a double bond.
• Total number of Resonating structures ${\mathrm{SO}}_2$ is $2$
• However theoretically there is a third structure also which has no covalent charges and more covalent bonds than on any atom.

Resonance structure for ${\mathrm{CO}}_2$:

• ${\mathrm{CO}}_2$has '$16$'valence electrons in which are from $4$ Carbon and $6$ from Oxygen
• The three resonating structures ${\mathrm{CO}}_2$are:

• The above resonating structure however full octets and the first structure are the most stable.
• In 2 and 3 structures due to the presence of positive charge will be less stable.
• Total number of Resonating structures ${\mathrm{CO}}_2$ is $3$