Bisulfate ion (HSO4-) Ion Lewis Structure
Bisulfate (HSO4- ion contains one sulfur atom, one hydrogen atom and four oxygen atoms. Lewis structure of HSO4- contains two S=O bonds and two S-O bond. There is -1 charge on one oxygen atom in HSO4- lewis structure.
HSO4- lewis structure
 ion lewis structure.jpg "bisulfate ion (HSO4-) ion lewis structure")
Characteristics of HSO4- ion are listed below.
- Sulfur atom is located as the center atom and four oxygen atoms have made bonds with sulfur atom.
- There are two S=O double bonds two S-O bonds.
- As well, one oxygen has a -1 charge and three lone pairs on its valence shell.
Steps of drawing lewis structure of HSO4- ion
There are several guidelines to follow for lewis structure drawing. Number of steps can be changed according the complexity of the molecule or ion. Because HSO4- ion is an ion and there are five atoms, we will have more steps than drawing a simple molecule or ion. However, those all steps are mentioned and explained in detail in this tutorial to improve your knowledge about lewis structure.
- Find total number of electrons of the valance shells of sulfur atom, hydrogen atom and four oxygen atoms.
- Determine total electrons pairs existing as lone pairs and bonds
- Deciding center atom
- Mark lone pairs on atoms
- Mark charges on atoms if there are charges.
- Check the stability and minimize charges on atoms by converting lone pairs to bonds to obtain best lewis structure.
Total number of electrons of the valance shells of HSO4- ion
There are three elements in bisulfate ion; sulfur, hydrogen and oxygen. Oxygen is located in group VIA in the periodic table and oxygen contains six electrons in its last shell (valence shell). Also, Sulfur is a group VIA element in the periodic table and contains six electrons in its last shell. Hydrogen has only one electron in its valence shell. Now, we know how many electrons are there in valence shells of oxygen and bromine atoms.
- valence electrons given by sulfur atoms = 6 * 1 = 6
- valence electrons given by oxygen atoms = 6 * 4 = 24
- valence electrons given by hydrogen atom = 1 * 1 = 1
- Due to -1 charge, one electron should be added to the total number of valence electrons.
- Total valence electrons = 6 + 24 + 1 + 1 = 32
Total valence electrons pairs
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, HSO4- ion, total pairs of electrons are sixteen in their valence shells.
Center atom of HSO4- molecule
Hydrogen atom cannot be a center atom because hydrogen can only keep two electrons in its valence shell.
Because, sulfur can show higher valance (6) than oxygen (2) , bromine has the higher priority to be the center atom in HSO4-. Also, sulfur is more electropositive than oxygen, it again proves, sulfur should be the center atom.
 ion skeletal.jpg "center atom and skeletal of bisulfate ion (HSO4-)")
Lone pairs on atoms
After determining the center atom and sketch of HSO4- ion, we can start to mark lone pairs on atoms. Remember that, there are total of sixteen electron pairs.
- There are already five bonds in the above drawn skeletal. So, now there are eleven electron pairs are remaining to mark as lone pairs.
- Usually, those remaining electron pairs should be started to mark on outside atoms. Therefore, we can start to mark those remaining electrons pairs on oxygen atoms. Three oxygen atoms will take three lone pairs and one oxygen atom (which is joint with hydrogen atom) will two lone pairs.
- Now, all electron pairs are marked and no more lone pairs to mark on sulfur atom.
Mark charges on atoms
Except hydrogen atom and one oxygen atom, all other atoms have charges.
Check the stability and minimize charges on atoms by converting lone pairs to bonds
Because lot of atoms have charges and having a charge like +2 on sulfur atom, above structure has to consider as not stable. Therefore, we should try to reduce charges by converting lone pairs to bonds to find the most stable structures.
As below, we convert lone pairs of oxygen atoms to bonds in two steps.
With converting lone pairs to bonds, there are two double bonds in the new structure. You can see, charges has been reduced in new structure than previous structures. There is only -1 charge on one oxygen atom.
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