Cl2O (dichlorine monoxide) has two chlorine atoms and one oxygen atom. In the lewis structure of Cl2O, there are two single bonds around the oxygen atom, with two chlorine atoms attached to it. Each chlorine atom has three lone pairs, and the oxygen atom has two lone pairs.
Here’s how you can draw the Cl2O 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, chlorine has seven valence electrons and oxygen has six valence electrons.
Since Cl2O has two chlorine atoms and one oxygen atom, so…
Valence electrons of two chlorine atoms = 7 × 2 = 14
Valence electrons of one oxygen atom = 6 × 1 = 6
And the total valence electrons = 14 + 6 = 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 chlorine is less electronegative than oxygen, the central atom should be chlorine, right?
But if we place chlorine in the center and oxygen outside, and calculate the formal charge, then we do not get the formal charges on atoms closer to zero.
And the structure with the formal charges on atoms closer to zero is the best lewis structure.
Hence, here we have to assume that the central atom is oxygen.
Therefore, place oxygen in the center and chlorines 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 — Cl bonds are already marked. So we have to only mark the remaining eight electron pairs as lone pairs on the sketch.
Also remember that chlorine is a period 3 element, so it can keep more than 8 electrons in its last shell. And oxygen is a period 2 element, so it can not keep more than 8 electrons in its last shell.
Always start to mark the lone pairs from outside atoms. Here, the outside atoms are chlorines.
So for each chlorine, 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 each chlorine atom, formal charge = 7 – 6 – ½ (2) = 0
For oxygen atom, formal charge = 6 – 4 – ½ (4) = 0
Here, both chlorine and oxygen 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 Cl2O.
Next: CH3COOH Lewis Structure