Sulfur dioxide molecule contains one sulfur atom and two oxygen atoms. We will construct the lewis structure of SO2 molecule by following VSEPR theory rules and considering stability of intermediate structures. After obtaining the lewis structure of SO2, we can determine the hybridization of atoms.
Sulfur dioxide is a colourless inorganic gas and also a toxic gas. It gives a weak acid solution when dissolves in water. This gas is produced due to combustion of petroleum fuel in automobiles and industrial factories.
There are two double bonds between sulfur atom and oxygen atoms in SO molecule. Also, a lone pair exists on sulfur atom and each oxygen atom has two lone pairs in SO2 lewis structure.
All atoms have sp2 hybridization. Each oxygen atom has one sigma bond and two lone pairs. Therefore, oxygen atoms' hybridization should be sp2. For sulfur atom, there are two sigma bonds and one lone pair to make hybridization sp2.
Following steps are used to draw the lewis structure of SO2. Each step is explained in detail in next sections. If you are a beginner to lewis structure drawing, follow these sections slowly and properly to understand it completely. Look the figures to understand each step.
Both sulfur and oxygen belongs to the group VIA elements series. Therefore, they have six electrons in their valence shell. To find number of valence electron, these valence electrons of each element should be multiplied with their respective number of atoms in the molecule. Below, That step are done.
There are no charges in SO2 molecule. Therefore, no addition or reduction of valence electrons due to charges.
Total valance electrons pairs = σ bonds + π bonds + lone pairs at valence shells
Total electron pairs are determined by dividing the number total valence electrons by two. For, SO2 molecule, Total number of pairs of electrons are 9.
There are some requirements to be the center atom. Having a high valence is a main requirement to be a center atom. For SO2 molecule, sulfur has the highest valence than and oxygen.
After drawing the sketch, we should start to mark lone pairs on atoms. In the drawn sketch, there are two bonds. between atoms.
Charges on atoms are important to find the most stable structure. Therefore, we need to find the most stable structure to obtain lewis structure. Therefore, we should try to find charges if there are.
After, marking electron pairs on atoms, we should mark charges of each atom. Each oxygen atoms will get a -1 charge and sulfur atom get a +2 charge. Because SO2 is a neutral molecule, overall charge of the molecule should be zero. The overall charge of the molecule is, (-1) * 2 + (+2) = 0.
When there are positive and negative charges on lot of atoms or higher charges (like +2, +3, -2, -3) on atoms in an ion or molecule, that structure is not stable. Therefore, We should try to reduce charges on atoms if it is a possible. In thee above structure, there are charges on oxygen atoms and sulfur atom. Now, we are going to reduce charges on these atoms as below.
There is only one lone pair on valence shell of sulfur atom.
There are lone pairs on all atoms in SO2. Sulfur atom has one lone pair and each oxygen atom has two lone pairs. Therefore, there are total of five lone pairs on last shells of each atom in SO2.
If we consider the shape of SO2, water, nitrogen dioxide, hydrogen sulfide, ozone have similar shape, bent. Also, if number of sigma bonds are is considered, water, nitrogen dioxide, hydrogen sulfide, sulfur dioxide all have two sigma bonds. Both SO2 and ozone has one lone pair on thei center atom.
Actually, this question is weird one. Rather than discussing similarities, it's good to discuss their differences. In NO2 lewis structure, there is an unpaired electron on nitrogen atom.