C2H2Cl2 lewis structure, molecular geometry, polar or nonpolar, isomers

Home C2H2Cl2 lewis structure and its molecular geometry

C2H2Cl2 lewis structure molecular geometry

Dichloroethene, also known as DCE has a chemical formula of C2H2Cl2. It appears as a colorless liquid with a chloroform-like odor.

In this article, we will discuss C2H2Cl2 lewis structure, molecular geometry, polar or nonpolar, its isomers, etc.

It is highly flammable and can be lethal in high-dose exposure. 

Name of MoleculeDichloroethene
Chemical formulaC2H2Cl2
Molecular geometry of C2H2Cl2Trigonal planar
HybridizationSp2
Isomers of C2H2Cl2

Three isomers are possible –

  • 1,1-Dichloroethene
  • Cis-1,2-Dichloroethene
  • Trans-1,2-Dichloroethene
NatureTwo isomers are polar and one isomer is nonpolar.
Total Valence electron for C2H2Cl224

How to draw lewis structure of C2H2Cl2?

C2H2Cl2 Lewis structure is made up of two carbon atoms, two hydrogens, and two chlorine atoms. Both carbon atoms are kept at the central position and other atoms are at the surrounding position in lewis’s structure. The lewis structure of C2H2Cl2 contains one double bond(C=C) and four single bonds.

The drawing process of the C2H2Cl2 lewis structure is easy and simple. Let’s see how to do it.

Follow some steps for drawing the Lewis structure for C2H2Cl2

1. Count total valence electron in C2H2Cl2

In the very first step, we will count the total valence electron in the C2H2Cl2 molecule. To calculate the valence electron, look at the periodic group of the individual atoms – carbon, hydrogen, and chlorine.

The chlorine atom belongs to the periodic group 7A or 17th in the periodic table, hence, the valence electron for chlorine is 7.

The carbon atom is situated in the 14 or 4A periodic group, hence, its valence electron is 4. The hydrogen atom has only one valence electron.

valence electrons in carbon atom = 4

Valence electron in chlorine atom = 7

⇒ Valence electron in hydrogen atom = 1

∴ Total number of valence electrons available for the C2H2Cl2 Lewis structure = 4(2) + 1(2) + 7(2) = 24 valence electrons         [∴ C2H2Cl2 molecule has two carbon, two hydrogen, and two chlorine atoms]

valence electrons in C2H2Cl2 lewis structure

2. Find the least electronegative atom and place it at center

Now we will find the least electronegative atom in the C2H2Cl2 compound, after that, we will place it at the center in the lewis diagram and the rest atoms will be spread around it.

The electronegativity value of the carbon atom is 2.55, for a chlorine atom, it is 3.16.

“Hydrogen atoms always go on the outside of a Lewis Structure”.

Hence, the carbon atom is the least electronegative atom in the C2H2Cl2 compound, therefore, we will put both carbon atoms at a central position and (chlorine and hydrogen atom) at the respective position as shown in the figure.

central atom in C2H2Cl2 lewis structure

3. Connect outer atoms to central atom with a single bond

In this step, we simply connect each outer atom(chlorine and hydrogen) to the central atom (carbon) with the help of a single bond. Also, we will join both carbon atoms with a single bond as well.

C2H2Cl2 skeletal structure

Now count the valence electron used in the above structure. A single bond means two electrons, in the above structure, five single bonds are used.

Therefore, (5 single bonds × 2) = 10 valence electrons are used in the above structure from the total of 24 valence electrons available for drawing the lewis structure of C2H2Cl2.

∴ (24 – 10) = 14 valence electrons

So, we are left with 14 valence electrons more.

4. Place remaining electrons on outer atoms and complete their octet

In this step, we will put the remaining valence electron on the outer atom first for completing their octet. In a C2H2Cl2 molecule, the outer atom is hydrogen and chlorine.

⇒ Hydrogen atoms only need two valence electrons to fulfill the outer shell.

⇒ A chlorine atom needs 8 electrons to complete the outer shell.

completing octet of outer atoms in C2H2Cl2

As you see in the above figure, we have placed the 6 electrons represented as dots around both chlorine atoms.

∴ Chlorine atoms completed their octet since they have 8 electrons(6 electrons represented as dots + 2 electrons in a single bond).

∴ Hydrogen atoms already completed their octet since they are joined with one single bond means 2 electrons and remember, hydrogen only needs 2 electrons to have a full outer shell.

Now once again count the total valence electron in the above structure.

(5 single bond × 2 electrons + 12 electrons represented as dots) = 22 valence electrons are used in the above structure.

Remember, we had a total of 24 valence electrons available for drawing the lewis structure of C2H2Cl2, and in the above structure, we used 22 valence electrons.

So, we are still left with 2 valence electrons.

5. Complete the octet of the central atom

We know, the carbon atom is the central atom, and it requires a total of 8 electrons to have a full outer shell. We have 2 remaining valence electrons, so, just put these two valence electrons on the carbon atom.

completing central atom octet in C2H2Cl2

So, we used all the valence electrons that are available for the lewis structure of C2H2Cl2. And by looking at the above structure, we see, the right side carbon atom has 8 electrons(3 single bonds means 6 electrons + 2 electrons represented as dots).

But the left side carbon has only 6 electrons(3 single bonds) which means, it shorts 2 electrons.

For overcoming this problem, move the 2 valence electrons of right side carbon atom into the center to form a double bond.

converting lone pair to covalent bonds in C2H2Cl2 lewis structure

That’s all, now both carbon atoms have full outer shells since each of them has 8 electrons(2 single bonds means 4 electrons + 1 double bond means 4 electrons).

Now just check the formal charge for the above structure to verify its stability.

6. Check the stability with the help of a formal charge concept

The lesser the formal charge on atoms, the better is the stability of the lewis diagram.

To calculate the formal charge on an atom. Use the formula given below-

⇒ Formal charge = (valence electrons – Nonbonding electrons –  1/2 bonding electrons)

Let’s count the formal charge on the chlorine atom first(5th step structure).

For chlorine atom:

⇒ Valence electrons of chlorine = 7

⇒ Nonbonding electrons on chlorine= 6

⇒ Bonding electrons around chlorine(1 single bond) = 2

∴ (7 – 6 – 2/2) = 0 formal charge on chlorine atoms.

For hydorgen atom:

⇒ Valence electrons of hydrogen = 1

⇒ Nonbonding electrons on hydrogen = 0

⇒ Bonding electrons around hydrogen(1 single bond) = 2

∴ (1 – 0 – 2/2) = 0 formal charge on hydrogen atoms.

 For carbon atom

⇒ Valence electrons of carbon = 4

⇒ Nonbonding electrons on carbon = 0

⇒ Bonding electrons around carbon (2 single bonds + 1 double bond) = 8

∴ (4 – 0 – 8/2) = 0 formal charge on the carbon central atom as well.

C2H2Cl2 Lewis structure

C2H2Cl2 Lewis structure

So, all atoms in the above structure get a formal charge equal to zero, hence, this is our most stable and appropriate lewis structure of C2H2Cl2.

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What is the molecular geometry of C2H2Cl2?

The molecular geometry of C2H2Cl2 with respect to both carbon atoms is trigonal planar. Since both carbon central atom is bonded with three atoms(one hydrogen, one chlorine, and one another carbon) and it has no lone pair which means, it is an AX3 type molecule which implies its geometry will be trigonal planar.

A represent central atom

X represent the number of bonded atom to central atom

According to VSEPR theory or chart, the AX3 type molecule forms trigonal planar molecular geometry or shape.

molecular geometry or shape of C2H2Cl2

Isomers of C2H2Cl2

There are three isomers possible for C2H2Cl2. The three isomers are – 

  • 1,1-Dichloroethene
  • Cis-1,2-Dichloroethene
  • Trans-1,2-Dichloroethene

Isomers of C2H2Cl2

Is C2H2Cl2 polar or nonpolar?

Is C2H2Cl2 polar or non-polar? C2H2Cl2 exists as three isomers. Two isomers of C2H2Cl2 are polar and one isomer is nonpolar.

Three isomers of C2H2Cl2 is –

  • 1,1-Dichloroethene
  • Cis-1,2-Dichloroethene
  • Trans-1,2-Dichloroethene

The two isomers of C2H2Cl2 – 1, 1-Dichloroethene, and Cis-1, 2-Dichloroethene are polar. In a polar molecule, “the individual bond dipoles do not cancel each other. Hence, the molecule has a net non-zero dipole moment”.

The one isomer of C2H2Cl2 – Trans-1, 2-Dichloroethene is nonpolar. In the nonpolar isomer, “the individual bond dipoles cancel each other. Hence, the molecule has zero net dipole moment”.

is C2H2Cl2 polar or nonpolar

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FAQ

How many isomers exist for C2H2Cl2? Also, tell which is polar or nonpolar?

There are three isomers possible for C2H2Cl2.

  • 1,1-Dichloroethene isomer  (Polar)
  • Cis-1,2-Dichloroethene isomer  (Polar)
  • Trans-1,2-Dichloroethene isomer  (Nonpolar)

Why the molecular geometry of C2H2Cl2 is trigonal planar?

The lewis structure of C2H2Cl2 has two central atoms, both are carbon. Each carbon atom is attached to three atoms(one hydrogen, one chlorine, and one another carbon). Hence, the carbon atom has three regions of electron density.

According to VSEPR theory, the three region of electron density implies that the molecule will be Trigonal planar.

Therefore, the molecular geometry for C2H2Cl2 with respect to both carbon central atoms is Trigonal planar.

How many lone pairs are present in the C2H2Cl2 lewis structure?

The lone pair are represented as dots in the lewis diagram. In the C2H2Cl2 lewis structure, there are 12 dots electrons are present which means 6 lone pairs.

One lone pair means 2 dot electrons.

Hence, the number of lone pairs in the C2H2Cl2 lewis structure is 6. Three lone pairs on each chlorine atom.

Also Read:-

Preparation of C2H2Cl2

Simply, the C2H2Cl2 is produced by the controlled chlorination of acetylene.

⇒ C2H2 + Cl2 → C2H2Cl2

Properties and uses of C2H2Cl2

  • The boiling point for cis-1,2-Dichloroethene is 60.2 ºC and its melting point is −81.47 °C.
  • The boiling point for trans-1,2-Dichloroethene is 48.5 °C and its melting point is −49.44 °C.
  • It smells like acrid, chloroform.
  • It appears as a clear liquid with a harsh odor.
  • It is highly flammable and soluble in water.
  • The cis-isomer of C2H2Cl2 is more stable than its trans-isomers.
  • It is used in cleaning such as electronics cleaning and various metals cleaning.

Summary

  • The total valence electron is available for drawing the C2H2Cl2 lewis structure is 24.
  • The molecular geometry of C2H2Cl2 for both carbon central atoms is Trigonal planar.
  • In the C2H2Cl2 lewis structure, there are 4 single bonds, one double bond, and a total of 6 lone pairs are present.
  • C2H2Cl2 has three isomers – 1, 1-Dichloroethene, Cis-1, 2-Dichloroethene, Trans-1, 2-Dichloroethene.
  • The two isomers of C2H2Cl2 named – 1, 1-Dichloroethene and Cis-1, 2-Dichloroethene are polar. They have some net dipole moment.
  • The one isomer of C2H2Cl2 named – Trans-1, 2-Dichloroethene is nonpolar. It has zero dipole moment.
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