Lewis structure of sulfuric acid is drawn step by step in this tutorial. Total valence electrons concept is used to draw the lewis structure of H2SO4. Sulfuric acid is a strong dibasic acid.
Sulfuric acid is a dibasic strong acid. It means, it can release two hydrogen atoms to show acidic characteristics. Therefore, we can assume, there should be two -OH bonds in sulfuric acid molecule.
Most stable lewis structure of H2SO4 is shown below.
Following steps are followed to draw theH2SO4 lewis structure and they are explained in detail in next sections. If you are are beginner to lewis structure drawing, follow these sections slowly and properly to understand.
Drawing the correct lewis structure is important to draw resonance structures correctly
Both Sulfur and oxygen atoms are located at VIA group in the periodic table. So, oxygen and sulfur atoms have six electrons in their valence shells. Hydrogen is IA group element. Therefore it has only one electron in its last shell. Now, we can find the total valence electrons in the molecule.
There are four oxygen atoms in H2SO4 molecule, Therefore
There are two hydrogen atoms in H2SO4 molecule, Therefore
There are no charges in H2SO4 molecule.
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, H2SO4 molecule, Total pairs of electrons are 16.
There are some requirements to be the center atom. Having a high valence is a leading requirement to be a center atom. For H2SO4 molecule, sulfur has the highest valence than oxygen and hydrogen.
Because, sulfuric acid is a dibasic acid, it can release two H+ ions in the water. Therefore, there should be two -OH groups in H2SO4 molecule.
Charges on atoms is important to find the most stable 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. Two oxygen atoms will get a -1 charge and sulfur atom get a +2 charge. Sulfuric acid is a neutral molecule and overall charge should be zero. The overall charge of ion is ( -1*2 + (+2) ) = 0.
When charges exist on lot of atoms in an ion or molecule, that structure is not stable. We should try to reduce charges on atoms as much as possible. Now, we are going to reduce charges on drawn structure.
You see charges of atoms are reduced. Now, there is no charge in one oxygen atom and charge of sulfur atom is reduced from +2 to +1. So we have an stable ion than out previous one.
You should know, sulfur can keep more than eight electrons in its last shell. Therefore we can convert one more lone pair of another oxygen atom to make a bond.
In new structure, charges of atoms are reduced than previous structure. Now there are no charges on atoms. This structure of H2SO4 is more stable than previous structures. So, this structure has more chance to be the lewis structure of H2SO4.
There are two single bonds (S-O) around sulfur atom. Also, there are another two single bonds (O-H) between oxygen and hydrogen atom. Therefore, there are total of four single bonds in H2SO4.