HF Lewis structure

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HF (hydrogen fluoride) has one hydrogen atom and one fluorine atom.

In the HF Lewis structure, there is a single bond between the hydrogen and fluorine atoms, and on the fluorine atom, there are three lone pairs.

Steps

Here’s how you can easily draw the HF Lewis structure step by step:

#1 Draw a rough skeleton structure
#2 Mention lone pairs on the atoms
#3 If needed, mention formal charges on the atoms

Now, let’s take a closer look at each step mentioned above.

#1 Draw a rough skeleton structure

• First, determine the total number of valence electrons

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

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

Since HF has one hydrogen atom and one fluorine atom, so…

Valence electrons of one hydrogen atom = 1 × 1 = 1
Valence electrons of one fluorine atom = 7 × 1 = 7

And the total valence electrons = 1 + 7 = 8

Learn how to find: Hydrogen valence electrons and Fluorine valence electrons

• Second, find the total electron pairs

We have a total of 8 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 = 8 ÷ 2 = 4

• 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.

Hence, here we have to assume that the central atom is fluorine.

• And finally, draw the rough sketch

#2 Mention lone pairs on the atoms

Here, we have a total of 4 electron pairs. And one H — F bond is already marked. So we have to only mark the remaining three 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 fluorine is a period 2 element, so it can not keep more than 8 electrons in its last shell.

Always start to mark the lone pairs from outside atoms. Here, the outside atom is fluorine.

So for fluorine, there are three lone pairs, and for hydrogen, there is zero lone pair because all three electron pairs are over.

Mark the lone pairs on the sketch as follows:

#3 If needed, mention formal charges on the atoms

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

Here, both hydrogen and fluorine atoms do not have charges, so no need to mark the charges.

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

Therefore, this structure is the stable Lewis structure of HF.

Next: SCl₂ Lewis structure

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External links

• https://techiescientist.com/hf-lewis-structure/
• https://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/HF-lewis-structure.html
• https://lambdageeks.com/hf-lewis-structure/
• https://sciedutut.com/hf-lewis-structure/