C2H2Br2 Lewis structure

C₂H₂Br₂ (1,2-dibromoethylene) has two carbon atoms, two hydrogen atoms, and two bromine atoms.

In the C₂H₂Br₂ Lewis structure, there is a double bond between the two carbon atoms, and each carbon is attached with one hydrogen atom and one bromine atom, and on each bromine atom, there are three lone pairs.

Alternative method: Lewis structure of C₂H₂Br₂

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 bromine lies in group 17.

Hence, carbon has four valence electrons, hydrogen has one valence electron, and bromine has seven valence electrons.

Since C₂H₂Br₂ has two carbon atoms, two hydrogen atoms, and two bromine atoms, so…

Valence electrons of two carbon atoms = 4 × 2 = 8
Valence electrons of two hydrogen atoms = 1 × 2 = 2
Valence electrons of two bromine atoms = 7 × 2 = 14

And the total valence electrons = 8 + 2 + 14 = 24

Learn how to find: Carbon valence electrons, Hydrogen valence electrons, and Bromine valence electrons

• Second, find the total electron pairs

We have a total of 24 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 = 24 ÷ 2 = 12

• 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 bromine. Place the least electronegative atom at the center.

Since carbon is less electronegative than bromine, 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 bromine on either side.

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 12 electron pairs. And five bonds are already marked. So we have to only mark the remaining seven 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 bromine is a period 4 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 bromines, hydrogens, and right carbon. But no need to mark on hydrogen, because each hydrogen has already two electrons.

So for each bromine, there are three lone pairs, for right carbon, there is one lone pair, and for left carbon, there is zero lone pair because all seven 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 left carbon atom, formal charge = 4 – 0 – ½ (6) = +1

For right carbon atom, formal charge = 4 – 2 – ½ (6) = -1

For each hydrogen atom, formal charge = 1 – 0 – ½ (2) = 0

For each bromine atom, formal charge = 7 – 6 – ½ (2) = 0

Here, both carbon atoms have charges, so mark them on the sketch as follows:

The above structure is not a stable Lewis structure because both carbon atoms have charges. Therefore, reduce the charges (as below) by converting lone pairs to bonds.

Convert a lone pair of the right carbon atom to make a new C — C bond with the left carbon atom as follows:

Final structure

The final structure of C₂H₂Br₂ (specifically 1,2-dibromoethene) features two central carbon atoms linked by a double covalent bond. In this arrangement, each carbon atom satisfies the octet rule by forming a double bond with the other carbon, a single bond with one hydrogen atom, and a single bond with one bromine atom. Within this layout, each bromine atom fulfills its octet by retaining three lone pairs alongside its single shared bond, while each hydrogen atom achieves a stable duet. This configuration represents the most stable state for the molecule because it results in a formal charge of zero for every atom involved. Accordingly, this specific electronic distribution serves as the definitive and most accurate Lewis representation of 1,2-dibromoethene.

Next: SbCl₅ Lewis structure

External video

• C2H2Br2 Lewis Structure: How to Draw the Lewis Structure for C2H2Br2 – YouTube • Wayne Breslyn

External links

• https://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/C2H2Br2-lewis-structure.html