Lewis Structure of CH3CN (With 6 Simple Steps to Draw!)

I’m super excited to teach you the lewis structure of CH3CN molecule in just 6 simple steps.

Infact, I’ve also given the step-by-step images for drawing the lewis dot structure of CH3CN molecule.

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

Lewis structure of CH3CN contains two Carbon atoms (C) at the center and they are surrounded by three Hydrogen atoms (H) and one Nitrogen atom (N). There is a triple bond between the Carbon atom (C) & Nitrogen atom (N) and the other atoms are single bonded with each other. The Nitrogen atom has 1 lone pair.

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 CH3CN).

6 Steps to Draw the Lewis Structure of CH3CN

Step #1: Calculate the total number of valence electrons

Here, the given molecule is CH3CN. In order to draw the lewis structure of CH3CN molecule, first of all you have to find the total number of valence electrons present in the CH3CN 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 CH3CN molecule

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 Nitrogen:

Nitrogen is a group 15 element on the periodic table. ^[3]

Hence, the valence electrons present in nitrogen is 5 (see below image).

Hence in a CH3CN molecule,

Valence electrons given by each Carbon (C) atom = 4
Valence electron given by each Hydrogen (H) atom = 1
Valence electrons given by Nitrogen (N) atom = 5
So, total number of Valence electrons in CH3CN molecule = 4 + 1(3) + 4 + 5 = 16

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 CH3CN molecule, if we compare the carbon atom (C), nitrogen atom (N) and hydrogen atom (H), then hydrogen is less electronegative than carbon and nitrogen. But as per the rule, we have to keep hydrogen outside.

So, carbon (which is less electronegative than nitrogen) should be placed in the center and the remaining hydrogen atoms as well as nitrogen atom will surround it.

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

Now in the above sketch of CH3CN molecule, put the two electrons (i.e electron pair) between the carbon atom, nitrogen atom and hydrogen atom to represent a chemical bond between them.

These pairs of electrons present between the Carbon (C), Nitrogen (N) and Hydrogen (H) atoms form a chemical bond, which bonds these atoms with each other in a CH3CN molecule.

Step #4: Complete the octet (or duplet) on outside atoms

Don’t worry, I’ll explain!

In the Lewis structure of CH3CN, the outer atoms are hydrogen atoms as well as nitrogen atom.

Hydrogen already has a duplet (see below image).

So now, you have to complete the octet on nitrogen atom (because nitrogen requires 8 electrons to have a complete outer shell).

Now, you can see in the above image that the nitrogen atom forms an octet.

Also, all the 16 valence electrons of CH3CN 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 CH3CN.

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 4 electrons. So it does not fulfill the octet rule.

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

Still, the octet of carbon atom is not fulfilled as it has only 6 electrons.

So again moving another electron pair from the nitrogen atom, we will get the following structure.

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 and the carbon atom is stable.

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), nitrogen atom (N) as well as each hydrogen atom (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 Nitrogen:
Valence electron = 5 (as it is in group 15)
Nonbonding electrons = 2
Bonding electrons = 6

Formal charge	=	Valence electrons	–	Nonbonding electrons	–	(Bonding electrons)/2
C	=	4	–	0	–	8/2	=	0
H	=	1	–	0	–	2/2	=	0
N	=	5	–	2	–	6/2	=	0

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

Hence, there will not be any change in the above structure and the above lewis structure of CH3CN is the final stable structure only.

Each electron pair (:) in the lewis dot structure of CH3CN represents the single bond ( | ). So the above lewis dot structure of CH3CN can also be represented as shown below.

Article by;

Jay Rana

Jay is an educator and has helped more than 100,000 students in their studies by providing simple and easy explanations on different science-related topics. With a desire to make learning accessible for everyone, he founded Knords Learning, an online learning platform that provides students with easily understandable explanations. Read more about our Editorial process.

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