Lewis structure of C2H2O

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The Lewis structure of C₂H₂O contains one triple bond and three single bonds, with two carbons in the center. The left carbon is attached with one hydrogen, and the right carbon is attached with oxygen and one other hydrogen. The oxygen atom has two lone pairs, and the carbon atom and hydrogen atom do not have any lone pair.

Steps

By using the following steps, you can easily draw the Lewis structure of C₂H₂O.

#1 Draw skeleton
#2 Show chemical bond
#3 Mark lone pairs
#4 Complete octet on central atom
#5 Calculate formal charge and check stability

Let’s one by one discuss each step in detail.

#1 Draw skeleton

In this step, first calculate the total number of valence electrons. And then, decide the central atom.

• Let’s calculate the total number of valence electrons

We know that… carbon is a group 14 element, hydrogen is a group 1 element, and oxygen is a group 16 element. Hence, carbon has four valence electrons, hydrogen has one valence electron, and oxygen has six valence electrons.

Now C₂H₂O has two carbon atoms, two hydrogen atoms, and one oxygen atom.

So the total number of valence electrons = (valence electrons of carbon atom × 2) + (valence electrons of hydrogen atom × 2) + valence electrons of oxygen atom

Therefore, the total number of valence electrons = 8 + 2 + 6 = 16

• Now decide the central atom

We can not assume hydrogen as the central atom, because the central atom is bonded with at least two other atoms. And hydrogen has only one electron in its last shell, so it can not make more than one bond.

Therefore, choose the central atom from carbon and oxygen.

The atom with the least electronegative value is placed at the center. By looking at the periodic table, we get the electronegativity values for carbon and oxygen as follows:

Electronegativity value of carbon = 2.55
Electronegativity value of oxygen = 3.44

Obviously, carbon is less electronegative than oxygen. Hence, assume that left carbon is the central atom (as there are two carbons).

So now, put two carbons in the center and two hydrogens and oxygen on either side. And draw the rough skeleton structure for the Lewis structure of C₂H₂O something like this:

Also read: How to draw Lewis structure of HPO₄^2- (5 steps)

#2 Show chemical bond

Place two electrons between the atoms to show a chemical bond. Since two carbons are surrounded by two hydrogens and oxygen, use eight electrons to show four chemical bonds as follows:

#3 Mark lone pairs

As calculated earlier, we have a total of 16 valence electrons. And in the above structure, we have already used eight valence electrons. Hence, eight valence electrons are remaining.

Two valence electrons represent one lone pair. So eight valence electrons = four lone pairs.

Note that both (carbon and oxygen) are the period 2 elements, so they can not keep more than 8 electrons in their last shell. And hydrogen is a period 1 element, so it can not keep more than 2 electrons in its last shell.

Also, make sure that you start marking these lone pairs on outside atoms first. And then, on the central atom.

The outside atoms are hydrogen, oxygen, and right carbon. But hydrogen can not keep more than 2 electrons in its last shell. Hence, don’t mark the lone pairs on hydrogen.

So oxygen and right carbon will get two lone pairs. And the central atom (left carbon) will not get any lone pair, because all four lone pairs are used.

Now draw the Lewis structure of C₂H₂O something like this:

In the above structure, you can see that the octet is completed on outside atoms. But, the central atom (left carbon) doesn’t form an octet.

So in the next step, we have to complete the octet on the central atom.

Also read: How to draw Lewis structure of C₆H₁₂ (3 steps)

#4 Complete octet on central atom

Remember that carbon is a period 2 element, so it can not keep more than 8 electrons in its last shell.

Now left carbon already has four valence electrons. Hence, left carbon needs four more valence electrons to complete its octet.

So convert two lone pairs from the right carbon atom to make a new bond with the left carbon atom. And then, the Lewis structure of C₂H₂O looks something like this:

In the above structure, you can see that the octet is completed on the central atom (left carbon), and also on the outside atoms. Therefore, the octet rule is satisfied.

After completing the octet, one last thing we need to do is, calculate the formal charge and check the stability of the above structure.

Also read: How to draw Lewis structure of POF₃ (5 steps)

#5 Calculate formal charge and check stability

The following formula is used to calculate the formal charges on atoms:

Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons

Collect the data from the above structure and then, write it down below as follows:

• For each carbon atom

Valence electrons = 4
Nonbonding electrons = 0
Bonding electrons = 8

Formal charge = 4 – 0 – ½ (8) = 0

• For each hydrogen atom

Valence electrons = 1
Nonbonding electrons = 0
Bonding electrons = 2

Formal charge = 1 – 0 – ½ (2) = 0

• For oxygen atom

Valence electrons = 6
Nonbonding electrons = 4
Bonding electrons = 4

Formal charge = 6 – 4 – ½ (4) = 0

Mention the formal charges of atoms on the structure. So the Lewis structure of C₂H₂O looks something like this:

In the above structure, you can see that the formal charges of all atoms are zero. Therefore, this is the stable Lewis structure of C₂H₂O.

And each horizontal line drawn in the above structure represents a pair of bonding valence electrons.

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Related

• Lewis structure of HPO₄^2-
• Lewis structure of C₆H₁₂
• Lewis structure of POF₃
• Lewis structure of H₃PO₃
• Lewis structure of CF₃Cl

External links

• Draw a Lewis structure for ketene, C2H2O which has a carbon-carbon double bond – Chegg
• Draw and explain the Lewis structure for C2H2O – Homework.Study.com
• Draw a Lewis structure for ketene, C2H2O , which has a carbon‑carbon double bond – Brainly
• Ethynol | C2H2O | CID 123441 – National Institutes of Health (.gov)
• Ethenone | C2H2O – ChemSpider
• What is the Lewis structure of c2h2o? – Answers
• Draw the Lewis structure of ketene (C2H2O) and describe the hybridization states of the C atoms – StudySoup
• Draw a Lewis structure for ketene, C2H2O which has a carbon-carbon double bond – Quizlet
• What is the Lewis structure of the ketene C2H2O? – OneClass
• Draw the Lewis structure of ketene (C2H2O) and de− scribe the hybridization states of the C atoms – Numerade
• C2H2O (Ketene) Oxidation Number – ChemicalAid