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.
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.
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.
Important: Drawing correct lewis structure is important to draw resonance structures correctly.
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.
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.
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.
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 no charges on oxygen atom and hydrogen atoms.
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.
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.
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.
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.