Lewis Structure of H2O (Water) - Drawing Steps
Lewis structure of water molecule contains two single bonds around oxygen atom. number of total valence electrons of oxygen and hydrogen atoms are used to draw lewis structure. Each step of drawing lewis structure of H2O are explained in this tutorial.
H2O lewis structure
In the lewis structure of H2O, there are two single bonds around oxygen atom. Hydrogen atoms are joint to oxygen atom through single bonds. Also, there are two lone pairs on oxygen atom.
Water molecule is a simple molecule. Drawing lewis structure of water molecule is simple than some of other complex molecules or ions. Imagine drawing lewis structure of thiosulfate ion.
Steps of drawing lewis structure of H2O
There are some steps to follow to draw a lewis structure properly. For H2O molecule, its lewis structure and those steps are explained in detail in this tutorial. Because water molecule is simple, some of these steps are not used much. In such cases, they are mentioned with respective steps.
- Find total number of electrons of the valance shells of hydrogen atoms and oxygen atom
- Total electrons pairs as lone pairs and bonds
- Center atom selection
- mark lone pairs on atoms
- Mark charges on atoms if there are.
- Check the stability and minimize charges on atoms by converting lone pairs to bonds to obtain best lewis structure.
Important: Drawing correct lewis structure is important to draw resonance structures correctly.
Total number of electrons of the valance shells of H2O
There are two of elements; hydrogen and oxygen. Hydrogen is a group IA element and has only one electron in its last shell (valence shell). Oxygen is a group VIA element in the periodic table and contains six electrons in its last shell. Now we know how many electrons are includes in valence shells of each atom.
- valence electrons given by hydrogen atoms = 1 * 2 = 2
- valence electrons given by oxygen atoms = 6*1 = 6
- Total valence electrons = 2 + 6 = 8
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, H2O, Total pairs of electrons are 4 in their valence shells.
Center atom of H2O
To be the center atom, ability of having greater valance is important. Then, from hydrogen and oxygen, which atom has the highest valence? Maximum valence of oxygen is two. hydrogen's only valence is one. Therefore, oxygen atom should be the center atom of H2O. Now, we can draw a sketch of H2O to show how atoms are located in the molecule.
Lone pairs on atoms
After determining the center atom and sketch of H2O molecule, we should start to mark lone pairs on atoms. Remember that, there are total of four electron pairs.
- There are already two H-O bonds in the drawn sketch structure. Now <>only two (4-2) electron pairs are remaining to mark on atoms.
- Usually, those remaining electron pairs should be started to mark on outside atoms. But in H2O, hydrogen atom are the outside atoms which cannot keep more than two electron in its last shell. Therefore, we cannot mark those two electrons pairs on hydrogen atoms.
- Then, mark those two electrons pairs on center atom; oxygen
Mark charges on atoms
There are no charges on oxygen atom and hydrogen atoms.
Check the stability and minimize charges on atoms by converting lone pairs to bonds
If molecule or ion contains so many charges on atoms, that structure is not stable. If we got a such structure, we should try to minimize charges by converting lone pairs to bonds.
Because there is no charges on atoms, no need to reduce charges as a step of drawing best lewis structure. Already, we got the best lewis structure for H2O.
Questions
What are the other ways drawing lewis structure for water?
In this tutorial, we took total electrons in last shells of elements (oxygen and hydrogen atoms). Instead of that, we can valence of oxygen is two and those two electrons should be used to make bonds with two hydrogen atoms.
How many lone pairs are there on oxygen atom in H2O lewis structure?
There are only two lone pairs on oxygen atom. The only atom which has lone pairs in H2O is oxygen because hydrogen has already made a bond with oxygen.
What are the similar lewis structures to water can be drawn for?
In lewis structure of water molecule, there are two sigma bonds and two lone pairs around sulfuratom. Hydrogen sulfide, oxygen difluoride (F2O) have similar lewis structures to water.