Lewis structure of C2HCl

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The Lewis structure of C₂HCl contains one triple bond and two single bonds, with two carbons in the center. The left carbon is attached with hydrogen, and the right carbon is attached with chlorine. There are three lone pairs on the chlorine atom, and hydrogen atom and carbon atom do not have any lone pair.

Steps

By using the following steps, you can easily draw the Lewis structure of C₂HCl.

#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 chlorine is a group 17 element. Hence, carbon has four valence electrons, hydrogen has one valence electron, and chlorine has seven valence electrons.

Now C₂HCl has two carbon atoms, one hydrogen atom, and one chlorine atom.

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

Therefore, the total number of valence electrons = 8 + 1 + 7 = 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 chlorine.

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 chlorine as follows:

Electronegativity value of carbon = 2.55
Electronegativity value of chlorine = 3.16

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

So now, put two carbons in the center and hydrogen and chlorine on either side. And draw the rough skeleton structure for the Lewis structure of C₂HCl something like this:

Also read: How to draw Lewis structure of HO₂^– (4 steps)

#2 Show chemical bond

Place two electrons between the atoms to show a chemical bond. Since two carbons are surrounded by hydrogen and chlorine, use six electrons to show three 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 six valence electrons. Hence, ten valence electrons are remaining.

Two valence electrons represent one lone pair. So ten valence electrons = five lone pairs.

Note that carbon is a period 2 element, so it can not keep more than 8 electrons in its last shell. Hydrogen is a period 1 element, so it can not keep more than 2 electrons in its last shell. And chlorine is period 3 element, so it can keep more than 8 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, chlorine, 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 chlorine will get three lone pairs, and right carbon will get two lone pairs. And the central atom (left carbon) will not get any lone pair, because all five lone pairs are used.

Now draw the Lewis structure of C₂HCl 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 TeF₄ (4 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 C₂HCl 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 SO (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 hydrogen atom

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

Formal charge = 1 – 0 – ½ (2) = 0

• For chlorine atom

Valence electrons = 7
Nonbonding electrons = 6
Bonding electrons = 2

Formal charge = 7 – 6 – ½ (2) = 0

Mention the formal charges of atoms on the structure. So the Lewis structure of C₂HCl 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 C₂HCl.

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

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Related

• Lewis structure of HO₂^–
• Lewis structure of TeF₄
• Lewis structure of SO
• Lewis structure of CH₂
• Lewis structure of AlF₃

External links

• C2HCl Lewis Structure in 6 Steps (With Images) – Pediabay
• Draw the Lewis structure of C2HCl and identify its geometry – Homework.Study.com
• Chloroethyne | C2HCl | CID 68975 – National Institutes of Health (.gov)
• Draw Lewis structures for the chloroethyne molecule (C2HCl) – Chegg
• Lewis structure of c2hcl – Brainly
• Draw a valid Lewis structure of HBr, and C2HCl – Course Hero