C2H4Cl2 (1,2-dichloroethane) has two carbon atoms, four hydrogen atoms, and two chlorine atoms.
In C2H4Cl2 Lewis structure, there is a single bond between the two carbon atoms, and each carbon is attached with one chlorine atom and one hydrogen atom. And on each chlorine atom, there are three lone pairs.
Alternative method: Lewis structure of C2H4Cl2
Rough sketch
- First, determine the total number of valence electrons
In the periodic table, carbon lies in group 14, hydrogen lies in group 1, and chlorine lies in group 17.
Hence, carbon has four valence electrons, hydrogen has one valence electron, and chlorine has seven valence electrons.
Since C2H4Cl2 has two carbon atoms, four hydrogen atoms, and two chlorine atoms, so…
Valence electrons of two carbon atoms = 4 × 2 = 8
Valence electrons of four hydrogen atoms = 1 × 4 = 4
Valence electrons of two chlorine atoms = 7 × 2 = 14
And the total valence electrons = 8 + 4 + 14 = 26
Learn how to find: Carbon valence electrons, Hydrogen valence electrons, and Chlorine valence electrons
- Second, find the total electron pairs
We have a total of 26 valence electrons. And when we divide this value by two, we get the value of total electron pairs.
Total electron pairs = total valence electrons ÷ 2
So the total electron pairs = 26 ÷ 2 = 13
- Third, determine the central atom
Here hydrogen can not be 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.
Now we have to choose the central atom from carbon and chlorine. Place the least electronegative atom at the center.
Since carbon is less electronegative than chlorine, assume that the central atom is carbon.
Here, there are two carbon atoms, so we can assume any one as the central atom.
Let’s assume that the central atom is left carbon.
Therefore, place carbons in the center and hydrogen and chlorine on either side.
- And finally, draw the rough sketch
Lone pair
Here, we have a total of 13 electron pairs. And seven bonds are already marked. So we have to only mark the remaining six electron pairs as lone pairs on the sketch.
Also remember 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 a period 3 element, so it can keep more than 8 electrons in its last shell.
Always start to mark the lone pairs from outside atoms. Here, the outside atoms are hydrogens, chlorines, and right carbon. But no need to mark on hydrogen, because each hydrogen has already two electrons.
So for each chlorine, there are two lone pairs, and for left carbon and right carbon, there is zero lone pair because all six electron pairs are over.
Mark the lone pairs on the sketch as follows:
Formal charge
Use the following formula to calculate the formal charges on atoms:
Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons
For each carbon atom, formal charge = 4 – 0 – ½ (8) = 0
For each hydrogen atom, formal charge = 1 – 0 – ½ (2) = 0
For each chlorine atom, formal charge = 7 – 6 – ½ (2) = 0
Here, the atoms do not have charges, so no need to mark the charges.
Final structure
The final structure of C2H4Cl2 consists of two carbon atoms linked to each other by a single covalent bond, with each carbon further bonded to two hydrogen atoms and one chlorine atom. In this arrangement, both carbon atoms satisfy the octet rule by forming four single bonds each, while the chlorine atoms complete their octets by maintaining three lone pairs. Each hydrogen atom reaches its stable duet state through its single shared pair with carbon. This configuration is the most stable because it results in formal charges of zero for all atoms, representing the most energetically favorable state for the molecule. Consequently, this specific electronic distribution serves as the definitive and most accurate Lewis representation of 1,2-dichloroethane.
Next: CHClO Lewis structure
External links
- https://homework.study.com/explanation/draw-lewis-structures-for-each-molecular-formula-a-c2h4cl2-two-isomers-b-c3h8o-three-isomers-c-c3h6-two-isomers.html
- https://www.chegg.com/homework-help/questions-and-answers/draw-lewis-structures-aip-s-nf-c2h4cl2-ch40-sure-show-valence-electrons-dots-lines-bonds–q53348508
- https://www.studysmarter.us/textbooks/chemistry/organic-chemistry-5th/structure-and-bonding/q9-question-draw-lewis-structures-for-each-molecular-formula/
- https://www.bartleby.com/questions-and-answers/draw-lewis-structures-for-each-molecular-formula-a.-c2h4cl2-two-isomers-b.-c3h8o-three-isomers-c.-c3/f8d4779f-3797-4d04-b79d-c7baae54a4f8
Deep
Learnool.com was founded by Deep Rana, who is a mechanical engineer by profession and a blogger by passion. He has a good conceptual knowledge on different educational topics and he provides the same on this website. He loves to learn something new everyday and believes that the best utilization of free time is developing a new skill.