Lewis Structure of COCl2 (With 6 Simple Steps to Draw!)

Ready to learn how to draw the lewis structure of COCl2?

Awesome!

Here, I have explained 6 simple steps to draw the lewis dot structure of COCl2 (along with images).

So, if you are ready to go with these 6 simple steps, then let’s dive right into it!

Lewis structure of COCl2 contains a double bond between the Carbon (C) & Oxygen (O) atom and two single bonds between Carbon (C) & Chlorine (Cl) atoms. The Carbon atom (C) is at the center and it is surrounded by two Chlorine (Cl) and one Oxygen atom (O).

Let’s draw and understand this lewis dot structure step by step.

(Note: Take a pen and paper with you and try to draw this lewis structure along with me. I am sure you will definitely learn how to draw lewis structure of COCl2).

6 Steps to Draw the Lewis Structure of COCl2

Step #1: Calculate the total number of valence electrons

Here, the given molecule is COCl2. In order to draw the lewis structure of COCl2, first of all you have to find the total number of valence electrons present in the COCl2 molecule.
(Valence electrons are the number of electrons present in the outermost shell of an atom).

So, let’s calculate this first.

Calculation of valence electrons in COCl2

• For Carbon:

Carbon is a group 14 element on the periodic table. ^[1]

Hence, the valence electrons present in carbon is 4 (see below image).

• For Oxygen:

Oxygen is a group 16 element on the periodic table. ^[2]

Hence, the valence electron present in oxygen is 6 (see below image).

• For Chlorine:

Chlorine is a group 17 element on the periodic table. ^[3]

Hence, the valence electron present in chlorine is 7 (see below image).

Hence in a COCl2 molecule, 

Valence electrons given by Carbon (C) atom = 4
Valence electrons given by Oxygen (O) atom = 6
Valence electrons given by each Chlorine (Cl) atom = 7
So, total number of Valence electrons in COCl2 molecule = 4 + 6 + 7(2) = 24

Step #2: Select the center atom

While selecting the center atom, always put the least electronegative atom at the center.

(Remember: Fluorine is the most electronegative element on the periodic table and the electronegativity decreases as we move right to left in the periodic table as well as top to bottom in the periodic table). ^[4]

Here in the COCl2 molecule, if we compare the carbon atom (C), oxygen atom (O) and chlorine atom (Cl), then the carbon is less electronegative.

So, carbon should be placed in the center and the oxygen atom as well as chlorine atom will surround it.

Step #3: Put two electrons between the atoms to represent a chemical bond

Now in the above sketch of COCl2 molecule, put the two electrons (i.e electron pair) between the carbon-oxygen atoms and carbon-chlorine atoms to represent a chemical bond between them.

These pairs of electrons present between the Carbon & Oxygen atoms as well as between the Carbon & Chlorine atoms form a chemical bond, which bonds these atoms with each other in a COCl2 molecule.

Step #4: Complete the octet (or duplet) on outside atoms. If the valence electrons are left, then put the valence electrons pair on the central atom

Don’t worry, I’ll explain!

In the Lewis structure of COCl2, the outer atoms are chlorine atoms and oxygen atom.

You also have to see whether the oxygen atom as well as chlorine atoms are forming an octet or not! (because oxygen and chlorine both require 8 electrons to have a complete outer shell).

You can see in the above image that both the chlorine atoms as well as one oxygen atom forms an octet.

Also, all the 24 valence electrons of COCl2 molecule (as calculated in step #1) are used in the above structure. So there are no remaining electron pairs.

Hence there is no change in the above sketch of COCl2.

Let’s move to the next step.

Step #5: Check whether the central atom has octet or not. If it does not have an octet, then move the electron pair from the outer atom to form a double bond or triple bond

In this step, we have to check whether the central atom (i.e carbon) has an octet or not. 

In simple words, we have to check whether the central Carbon (C) atom has 8 electrons or not.

As you can see from the above image, the central atom (i.e carbon) has only 6 electrons. So it does not fulfill the octet rule.

Now, in order to fulfill the octet of a carbon atom, we have to move the electron pair from the outer atom (i.e oxygen atom) to form a double bond.

Now you can see from the above image that the central atom (i.e carbon), is having 8 electrons. So it fulfills the octet rule.

Step #6: Final step – Check the stability of lewis structure by calculating the formal charge on each atom

Now, you have come to the final step and here you have to check the formal charge on carbon atom (C), oxygen (O) atom as well as chlorine atoms (Cl).

For that, you need to remember the formula of formal charge;

Formal charge = Valence electrons – Nonbonding electrons – (Bonding electrons)/2

• For Carbon:
  Valence electrons = 4 (as it is in group 14)
  Nonbonding electrons = 0
  Bonding electrons = 8
• For Oxygen:
  Valence electron = 6 (as it is in group 16)
  Nonbonding electrons = 4
  Bonding electrons = 4
• For Chlorine:
  Valence electron = 7 (as it is in group 17)
  Nonbonding electrons = 6
  Bonding electrons = 2

Formal charge	=	Valence electrons	–	Nonbonding electrons	–	(Bonding electrons)/2
C	=	4	–	0	–	8/2	=	0
O	=	6	–	4	–	4/2	=	0
Cl	=	7	–	6	–	2/2	=	0

So you can see above that the formal charges on carbon, oxygen as well as chlorine are “zero”.

Hence, there will not be any change in the above structure and the above lewis structure of COCl2 is the final stable structure only.

Each electron pair (:) in the lewis dot structure of COCl2 represents the single bond ( | ). So the above lewis dot structure of COCl2 can also be represented as shown below.

(Note: In step 5, if we had moved the electron pair from the chlorine atom, then there will be +1 and -1 charges on chlorine and oxygen respectively. But here we move the electron pair from the oxygen atom, which gives the more stable structure (having “zero” charges on all the atoms.))

Related lewis structures for your practice:
Lewis structure of BrF5
Lewis structure of NCl3
Lewis structure of CHCl3
Lewis structure of BrF3
Lewis structure of SF2

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