OF2 (oxygen difluoride) has one oxygen atom and two fluorine atoms. In the lewis structure of OF2, there are two single bonds around the oxygen atom, with two fluorine atoms attached to it. Each fluorine atom has three lone pairs, and the oxygen atom has two lone pairs.
Here’s how you can draw the OF2 lewis structure step by step.
Step #1: draw sketch
Step #2: mark lone pairs
Step #3: mark charges (if there are)
Let’s break down each step in detail.
#1 Draw Sketch
- First, determine the total number of valence electrons
Hence, oxygen has six valence electrons and fluorine has seven valence electrons.
Since OF2 has one oxygen atom and two fluorine atoms, so…
Valence electrons of one oxygen atom = 6 × 1 = 6
Valence electrons of two fluorine atoms = 7 × 2 = 14
And the total valence electrons = 6 + 14 = 20
- Second, find the total electron pairs
We have a total of 20 valence electrons. And when we divide this value by two, we get the value of total electron pairs.
Total electron pairs = total valence electrons ÷ 2
So the total electron pairs = 20 ÷ 2 = 10
- Third, determine the central atom
We have to place the least electronegative atom at the center.
Since oxygen is less electronegative than fluorine, assume that the central atom is oxygen.
Therefore, place oxygen in the center and fluorines on either side.
- And finally, draw the rough sketch
#2 Mark Lone Pairs
Here, we have a total of 10 electron pairs. And two O — F bonds are already marked. So we have to only mark the remaining eight electron pairs as lone pairs on the sketch.
Also remember that both (oxygen and fluorine) are the period 2 elements, so they can not keep more than 8 electrons in their last shell.
Always start to mark the lone pairs from outside atoms. Here, the outside atoms are fluorines.
So for each fluorine, there are three lone pairs, and for oxygen, there are two lone pairs.
Mark the lone pairs on the sketch as follows:
#3 Mark Charges
Use the following formula to calculate the formal charges on atoms:
Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons
For oxygen atom, formal charge = 6 – 4 – ½ (4) = 0
For each fluorine atom, formal charge = 7 – 6 – ½ (2) = 0
Here, both oxygen and fluorine atoms do not have charges, so no need to mark the charges.
And in the above structure, you can see that the central atom (oxygen) forms an octet. Hence, the octet rule is satisfied.
Therefore, this structure is the stable lewis structure of OF2.
Next: NF3 Lewis Structure