HOFO Lewis structure

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HOFO Lewis Structure
HOFO Lewis structure

HOFO has one hydrogen atom, two oxygen atoms, and one fluorine atom.

In HOFO Lewis structure, there is a single bond between the two oxygen atoms. The left oxygen is attached with one hydrogen atom, and the right oxygen is attached with one fluorine atom. Each oxygen atom has two lone pairs, and the fluorine atom has three lone pairs.


Use these steps to correctly draw the HOFO Lewis structure:

#1 First draw a rough sketch
#2 Mark lone pairs on the atoms
#3 Calculate and mark formal charges on the atoms, if required

Let’s discuss each step in more detail.

#1 First draw a rough sketch

  • First, determine the total number of valence electrons
Periodic table

In the periodic table, hydrogen lies in group 1, oxygen lies in group 16, and fluorine lies in group 17.

Hence, hydrogen has one valence electron, oxygen has six valence electrons, and fluorine has seven valence electrons.

Since HOFO has one hydrogen atom, two oxygen atoms, and one fluorine atom, so…

Valence electrons of one hydrogen atom = 1 × 1 = 1
Valence electrons of two oxygen atoms = 6 × 2 = 12
Valence electrons of one fluorine atom = 7 × 1 = 7

And the total valence electrons = 1 + 12 + 7 = 20

  • Second, find the total electron pairs

We have a total of 20 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 = 20 ÷ 2 = 10

  • 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 oxygen and fluorine. Place the least electronegative atom at the center.

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

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

Let’s assume that the central atom is right oxygen.

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

  • And finally, draw the rough sketch
HOFO Lewis Structure (Step 1)
Rough sketch of HOFO Lewis structure

#2 Mark lone pairs on the atoms

Here, we have a total of 10 electron pairs. And three bonds are already marked. So we have to only mark the remaining seven 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 (oxygen and fluorine) 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, fluorine, and left oxygen. But no need to mark on hydrogen, because hydrogen already has two electrons.

So for fluorine, there are three lone pairs, and for each oxygen, there are two lone pairs.

Mark the lone pairs on the sketch as follows:

HOFO Lewis Structure (Step 2)
Lone pairs marked, and got the stable Lewis structure of HOFO

#3 Calculate and mark formal charges on the atoms, if required

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 each oxygen atom, formal charge = 6 – 4 – ½ (4) = 0

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

Here, the atoms do not have charges, so no need to mark the charges.

In the above structure, you can see that the central atom (right oxygen) forms an octet. The outside atoms (fluorine and left oxygen) also form 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 HOFO.

Next: Urea Lewis structure

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