HNO Lewis structure

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HNO (nitroxyl) has one hydrogen atom, one nitrogen atom, and one oxygen atom.

In the HNO Lewis structure, there is a single bond between nitrogen and hydrogen atom, and a double bond between nitrogen and oxygen atom. The nitrogen atom has one lone pair, and the oxygen atom has two lone pairs.

Steps

To properly draw the HNO Lewis structure, follow these steps:

#1 Draw a rough sketch of the structure
#2 Next, indicate lone pairs on the atoms
#3 Indicate formal charges on the atoms, if necessary
#4 Minimize formal charges by converting lone pairs of the atoms
#5 Repeat step 4 if necessary, until all charges are minimized

Let’s break down each step in more detail.

#1 Draw a rough sketch of the structure

• First, determine the total number of valence electrons

In the periodic table, hydrogen lies in group 1, nitrogen lies in group 15, and oxygen lies in group 16.

Hence, hydrogen has one valence electron, nitrogen has five valence electrons, and oxygen has six valence electrons.

Since HNO has one hydrogen atom, one nitrogen atom, and one oxygen atom, so…

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

And the total valence electrons = 1 + 5 + 6 = 12

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

• Second, find the total electron pairs

We have a total of 12 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 = 12 ÷ 2 = 6

• 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 nitrogen and oxygen. 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 hydrogen and oxygen on either side.

• And finally, draw the rough sketch

#2 Next, indicate lone pairs on the atoms

Here, we have a total of 6 electron pairs. And two bonds are already marked. So we have to only mark the remaining four electron pairs as lone pairs on the sketch.

Also remember that hydrogen is a period 1 element, so it can not keep more than 2 electrons in its last shell. And 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 hydrogen and oxygen. But no need to mark on hydrogen, because hydrogen already has two electrons.

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

Mark the lone pairs on the sketch as follows:

#3 Indicate formal charges on the atoms, if necessary

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

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

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

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

For 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.

#4 Minimize formal charges by converting lone pairs of the atoms

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

In the above structure, you can see that the central atom (nitrogen) forms an octet. The outside atom (oxygen) also forms an octet, and hydrogen forms a duet. Hence, the octet rule and duet rule are satisfied.

Also, the above structure is more stable than the previous structures. Therefore, this structure is the stable Lewis structure of HNO.

Next: NI₃ Lewis structure

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