N2O3 Lewis structure

N₂O₃ (dinitrogen trioxide) has two nitrogen atoms and three oxygen atoms.

In the N₂O₃ Lewis structure, there is a single bond between the two nitrogen atoms. The left nitrogen is attached with two oxygen atoms, and the right nitrogen is attached with one oxygen atom. One oxygen atom with a single bond has three lone pairs, and the two oxygen atoms with double bonds have two lone pairs.

Also, there is a negative (-1) charge on the oxygen atom with a single bond, and a positive (+1) charge on the left nitrogen atom.

Alternative method: Lewis structure of N₂O₃

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, nitrogen lies in group 15, and oxygen lies in group 16.

Hence, nitrogen has five valence electrons and oxygen has six valence electrons.

Since N₂O₃ has two nitrogen atoms and three oxygen atoms, so…

Valence electrons of two nitrogen atoms = 5 × 2 = 10
Valence electrons of three oxygen atoms = 6 × 3 = 18

And the total valence electrons = 10 + 18 = 28

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

• Second, find the total electron pairs

We have a total of 28 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 = 28 ÷ 2 = 14

• Third, determine the central atom

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

Since nitrogen is less electronegative than oxygen, assume that the central atom is nitrogen.

Here, there are two nitrogen atoms, so we can assume any one as the central atom.

Let’s assume that the central atom is left nitrogen.

Therefore, place nitrogens in the center and oxygens on either side.

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 14 electron pairs. And four bonds are already marked. So we have to only mark the remaining ten electron pairs as lone pairs on the sketch.

Also remember that both (nitrogen and oxygen) 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 oxygens and right nitrogen.

So for each oxygen, there are three lone pairs, and for right nitrogen, there is one lone pair.

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 nitrogen atom, formal charge = 5 – 0 – ½ (6) = +2

For right nitrogen atom, formal charge = 5 – 2 – ½ (4) = +1

For each oxygen atom, formal charge = 6 – 6 – ½ (2) = -1

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

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

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

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

Final structure

The final structure of N₂O₃ has two nitrogen atoms connected to each other by a single covalent bond. Within this layout, one nitrogen atom is double-bonded to a single oxygen atom, while the second nitrogen atom is bonded to two oxygen atoms—one through a double bond and the other via a single bond. The nitrogen atom associated with two oxygens carries a formal charge of +1, and the single-bonded oxygen atom carries a formal charge of -1, while the rest of the atoms maintain a formal charge of zero. To satisfy the octet rule, the double-bonded oxygens each retain two lone pairs, the single-bonded oxygen holds three lone pairs, and the nitrogen atom in the nitroso group (-N=O) keeps one lone pair. Although this structure contains formal charges, it is the most stable arrangement as it allows for significant resonance and avoids the instability of oxygen-bridged chains. Accordingly, this specific electronic distribution serves as the definitive and most accurate Lewis representation of dinitrogen trioxide.

Next: H₂PO₄^– Lewis structure

External video

• N2O3 Lewis Structure: How to Draw the Lewis Structure for N2O3 – YouTube • Wayne Breslyn

External links

• https://www.chemistryscl.com/general/lewis-structure-of-N2O3/
• https://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/N2O3-lewis-structure.html
• https://lambdageeks.com/n2o3-lewis-structure/