Lewis Structure of CH2O (With 6 Simple Steps to Draw!)

I’m super excited to teach you the lewis structure of CH2O in just 6 simple steps.

Infact, I’ve also given the step-by-step images for drawing the lewis dot structure of CH2O molecule.

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

Lewis structure of CH2O contains a double bond between the Carbon (C) & Oxygen (O) atom and two single bonds between Carbon (C) & Hydrogen (H) atoms. The Carbon atom (C) is at the center and it is surrounded by two Hydrogen (H) and one Oxygen atom (O). The Oxygen atom has 2 lone pairs.

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 CH2O).

6 Steps to Draw the Lewis Structure of CH2O

Step #1: Calculate the total number of valence electrons

Here, the given molecule is CH2O. In order to draw the lewis structure of CH2O, first of all you have to find the total number of valence electrons present in the CH2O 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 CH2O

• 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 Hydrogen: 

Hydrogen is a group 1 element on the periodic table. ^[2]

Hence, the valence electron present in hydrogen is 1 (see below image).

• For Oxygen:

Oxygen is a group 16 element on the periodic table. ^[3]

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

Hence in a CH2O molecule, 

Valence electrons given by Carbon (C) atom = 4
Valence electron given by each Hydrogen (H) atom = 1
Valence electrons given by Oxygen (O) atom = 6
So, total number of Valence electrons in CH2O molecule = 4 + 1(2) + 6 = 12

Step #2: Select the center atom (H is always outside)

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 CH2O molecule, if we compare the carbon atom (C) and oxygen atom (O), then the carbon is less electronegative than oxygen.

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

Also as per the rule, we have to keep hydrogen outside.

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

Now in the above sketch of CH2O molecule, put the two electrons (i.e electron pair) between the carbon-oxygen atoms and carbon-hydrogen atoms to represent a chemical bond between them.

These pairs of electrons present between the Carbon & Oxygen atoms as well as between the Carbon & Hydrogen atoms form a chemical bond, which bonds these atoms with each other in a CH2O 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 CH2O, the outer atoms are hydrogen atoms and oxygen atom.

So now, you have to check whether these hydrogen atoms are forming a duplet or not! (because hydrogen requires only 2 electrons to have a complete outer shell).

You also have to see whether the oxygen atom is forming an octet or not! (because oxygen requires 8 electrons to have a complete outer shell).

You can see in the above image that both the hydrogen atoms form a duplet. And the oxygen atom also forms an octet.

Also, all the 12 valence electrons of CH2O 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 CH2O.

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 hydrogen atoms (H).

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 Hydrogen:
  Valence electron = 1 (as it is in group 1)
  Nonbonding electrons = 0
  Bonding electrons = 2
• For Oxygen:
  Valence electron = 6 (as it is in group 16)
  Nonbonding electrons = 4
  Bonding electrons = 4

Formal charge	=	Valence electrons	–	Nonbonding electrons	–	(Bonding electrons)/2
C	=	4	–	0	–	8/2	=	0
H	=	1	–	0	–	2/2	=	0
O	=	6	–	4	–	4/2	=	0

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

Hence, there will not be any change in the above structure and the above lewis structure of CH2O is the final stable structure only.

Each electron pair (:) in the lewis dot structure of CH2O represents the single bond ( | ). So the above lewis dot structure of CH2O can also be represented as shown below.

Related lewis structures for your practice:
Lewis structure of SO3
Lewis structure of C2H4
Lewis structure of SF4
Lewis structure of H2S
Lewis structure of OF2

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