Lewis Structure of NO2-

Lewis Structure of NO2-

NO2 (nitrite) has one nitrogen atom and two oxygen atoms. In the lewis structure of NO2, there is one double bond and one single bond around the nitrogen atom, with two oxygen atoms attached to it. The oxygen atom with a double bond has two lone pairs, the oxygen atom with a single bond has three lone pairs, and the nitrogen atom has one lone pair.

Also, there is a negative (-1) charge on the oxygen atom with a single bond.

Steps

Here’s how you can draw the lewis structure of NO2 step by step.

Step #1: draw sketch
Step #2: mark lone pairs
Step #3: mark charges
Step #4: minimize charges
Step #5: minimize charges again (if there are)

Let’s break down each step in detail.

#1 Draw 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 NO2 has one nitrogen atom and two oxygen atoms, so…

Valence electrons of one nitrogen atom = 5 × 1 = 5
Valence electrons of two oxygen atoms = 6 × 2 = 12

Now the NO2 has a negative (-1) charge, so we have to add one more electron.

So the total valence electrons = 5 + 12 + 1 = 18

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

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

  • And finally, draw the rough sketch
Lewis Structure of NO2- (Step 1)

#2 Mark Lone Pairs

Here, we have a total of 9 electron pairs. And two N — O bonds are already marked. So we have to only mark the remaining seven 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.

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

Mark the lone pairs on the sketch as follows:

Lewis Structure of NO2- (Step 2)

#3 Mark Charges

Use the following formula to calculate the formal charges on atoms:

Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons

For 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:

Lewis Structure of NO2- (Step 3)

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.

#4 Minimize Charges

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

Lewis Structure of NO2- (Step 4)

In the above structure, you can see that the central atom (nitrogen) forms an octet. Hence, the octet rule is satisfied.

Now there is still a negative (-1) charge on the oxygen atom.

This is okay, because the structure with a negative charge on the most electronegative atom is the best lewis structure. And in this case, the most electronegative element is oxygen.

Also, the above structure is more stable than the previous structures. Therefore, this structure is the most stable lewis structure of NO2.

And since the NO2 has a negative (-1) charge, mention that charge on the lewis structure by drawing brackets as follows:

Lewis Structure of NO2- (Final)

Next: HClO3 Lewis Structure

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