NOCl Lewis Structure

NOCl Lewis Structure

NOCl (nitrosyl chloride) has one nitrogen atom, one oxygen atom, and one chlorine atom. In the lewis structure of NOCl, there is a double bond between nitrogen and oxygen atom, and a single bond between nitrogen and chlorine atom. The nitrogen atom has one lone pair, the oxygen atom has two lone pairs, and the chlorine atom has three lone pairs.

Steps

Here’s how you can draw the NOCl lewis structure 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, oxygen lies in group 16, and chlorine lies in group 17.

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

Since NOCl has one nitrogen atom, one oxygen atom, and one chlorine atom, so…

Valence electrons of one nitrogen atom = 5 × 1 = 5
Valence electrons of one oxygen atom = 6 × 1 = 6
Valence electrons of one chlorine atom = 7 × 1 = 7

And the total valence electrons = 5 + 6 + 7 = 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 and chlorine, assume that the central atom is nitrogen.

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

  • And finally, draw the rough sketch
NOCl Lewis Structure (Step 1)

#2 Mark Lone Pairs

Here, we have a total of 9 electron pairs. And two 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. 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 oxygen and chlorine.

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

Mark the lone pairs on the sketch as follows:

NOCl Lewis Structure (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 oxygen atom, formal charge = 6 – 6 – ½ (2) = -1

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

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

NOCl Lewis Structure (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:

NOCl Lewis Structure (Step 4)

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

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

Next: SeO2 Lewis Structure

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