C2N2 Lewis structure

C₂N₂ (cyanogen) has two carbon atoms and two nitrogen atoms.

In C₂N₂ Lewis structure, there is a single bond between the two carbon atoms, and each carbon is attached with one nitrogen atom, and on each nitrogen atom, there is one lone pair.

Alternative method: Lewis structure of C₂N₂

Contents

Rough sketch

First, determine the total number of valence electrons

In the periodic table, carbon lies in group 14, and nitrogen lies in group 15.

Hence, carbon has four valence electrons and nitrogen has five valence electrons.

Since C₂N₂ has two carbon atoms and two nitrogen atoms, so…

Valence electrons of two carbon atoms = 4 × 2 = 8
Valence electrons of two nitrogen atoms = 5 × 2 = 10

And the total valence electrons = 8 + 10 = 18

Learn how to find: Carbon valence electrons and Nitrogen valence electrons

Second, find the total electron pairs

We have a total of 18 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 = 18 ÷ 2 = 9

Third, determine the central atom

We have to place the least electronegative atom at the center.

Since carbon is less electronegative than nitrogen, 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 nitrogens on either side.

And finally, draw the rough sketch

C2N2 Lewis Structure (Step 1) — Rough sketch of C₂N₂ Lewis structure | Image: Learnool

Lone pair

Here, we have a total of 9 electron pairs. And three bonds are already marked. So we have to only mark the remaining six electron pairs as lone pairs on the sketch.

Also remember that both (carbon and nitrogen) are the period 2 elements, so they can not keep more than 8 electrons in their last shell.

Always start to mark the lone pairs from outside atoms. Here, the outside atoms are nitrogens and right carbon.

So for each nitrogen, there are three lone pairs, for both carbons, there is zero lone pair because all six electron pairs are over.

Mark the lone pairs on the sketch as follows:

C2N2 Lewis Structure (Step 2) — Lone pairs marked on C₂N₂ Lewis structure | Image: Learnool

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 (4) = +2

For each nitrogen atom, formal charge = 5 – 6 – ½ (2) = -2

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

C2N2 Lewis Structure (Step 3) — Formal charges marked on C₂N₂ Lewis structure | Image: Learnool

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

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

C2N2 Lewis Structure (Step 4) — Lone pair of left nitrogen is converted, and but still there are charges | Image: Learnool

Since there are charges on carbon and nitrogen atoms, again convert a lone pair of the left nitrogen atom to make a new C — N bond with the left carbon atom as follows:

C2N2 Lewis Structure (Step 5) — Lone pair of left nitrogen is converted again, but still there are charges | Image: Learnool

There are still charges on carbon and nitrogen atoms, so convert a lone pair of the right nitrogen atom to make a new C — N bond with the right carbon atom as follows:

C2N2 Lewis Structure (Step 6) — Lone pair of right nitrogen is converted, but still there are charges | Image: Learnool

The carbon and nitrogen atoms still have charges, so again convert a lone pair of the right nitrogen atom to make a new C — N bond with the right carbon atom as follows:

C2N2 Lewis Structure (Step 7) — Lone pair of right nitrogen is converted again, and got the stable Lewis structure of C₂N₂ | Image: Learnool

Final structure

The final structure of C₂N₂ comprises a linear chain of four atoms where two central carbon atoms are bonded to each other. In this arrangement, each carbon atom also forms a triple covalent bond with a nitrogen atom. Within this layout, both carbon atoms satisfy the octet rule by forming four total bonds (one single bond to the adjacent carbon and one triple bond to a nitrogen), while each nitrogen atom fulfills the octet rule by maintaining one lone pair alongside its triple bond. This configuration represents the most stable state for the molecule because it results in a formal charge of zero for every atom involved. Consequently, this specific electronic distribution serves as the definitive and most accurate Lewis representation of cyanogen.

Next: TeF₆ Lewis structure

External video

How to Draw the Lewis Dot Structure for C2N2: Cyanogen – YouTube • Wayne Breslyn

External links

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.