ClO– (hypochlorite) has one chlorine atom and one oxygen atom. In the lewis structure of ClO–, there is a single bond between the chlorine and oxygen atom, and on both chlorine and oxygen atoms, there are three lone pairs.
Also, there is a negative (-1) charge on the oxygen atom.
Here’s how you can draw the ClO– 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 ClO– has one chlorine atom and one oxygen atom, so…
Valence electrons of one chlorine atom = 7 × 1 = 7
Valence electrons of one oxygen atom = 6 × 1 = 6
Now the ClO– has a negative (-1) charge, so we have to add one more electron.
So the total valence electrons = 7 + 6 + 1 = 14
- Second, find the total electron pairs
We have a total of 14 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 = 14 ÷ 2 = 7
- Third, determine the central atom
We have to place the least electronegative atom at the center.
Since chlorine is less electronegative than oxygen, assume that the central atom is chlorine.
- And finally, draw the rough sketch
#2 Mark Lone Pairs
Here, we have a total of 7 electron pairs. And one Cl — O bond is already marked. So we have to only mark the remaining six 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 atom is oxygen.
So for each atom, there are three 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 chlorine atom, formal charge = 7 – 6 – ½ (2) = 0
For oxygen atom, formal charge = 6 – 6 – ½ (2) = -1
Here, the oxygen atom has a charge, so mark it on the sketch as follows:
In the above structure, you can see that the central atom (chlorine) forms an octet. Hence, the octet rule is satisfied.
Now there is still a negative (-1) charge on the oxygen atom.
This is okay, because the structure with a negative charge on the most electronegative atom is the best lewis structure. And in this case, the most electronegative element is oxygen.
Therefore, this structure is the most stable lewis structure of ClO–.
And since the ClO– has a negative (-1) charge, mention that charge on the lewis structure by drawing brackets as follows:
Next: NOCl Lewis Structure