Oxygen is a diatomic molecule and contains only two oxygen atoms. In the lewis structure of O2 molecule, a double bond is located between oxygen atoms and each oxygen atom has two lone pairs in their valence shells. There are many things to learn when we draw the O2 lewis structure.
There is a double bond between oxygen atoms and two lone pairs exist on each oxygen atom. There are several interesting steps in drawing oxygen molecule's lewis structure.
When we draw a lewis structure, there are several guidelines to follow. Number of steps in the guidelines can be changed according the complexity of the molecule or ion. Because O2 is a simple molecule, it is extremely easy to draw the lewis structure of it. However those all steps are mentioned and explained in detail in this tutorial for your knowledge.
There is only one element in the oxygen molecule. 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 there in valence shells of oxygen atoms.
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, O2 molecule, Total pairs of electrons are six in their valence shells.
Because, there are only two atoms and both atoms are oxygen, do not need to worry about center atom selection.
After determining the center atom and sketch of O2 molecule, we can start to mark lone pairs on atoms. Remember that, there are total of six electron pairs.
There are charges on both oxygen atoms. One oxygen atom has +1 charge and other oxygen atom has -1 charge.
Because, there are charges on both nitrogen atoms and those charges are large, above structure is not stable. Also, one oxygen atom des not have eight electrons in its last shell, So, above structure is very unstable and need to stable that. Therefore, we need to reduce charges as below by converting lone pairs to bonds.
In the last structure, you see there are no charges on oxygen atoms and valence shell has eight electrons to fulfill the octal in both oxygen atoms.