Lewis structure of PF3

The information on this page is ✔ fact-checked.

The Lewis structure of PF₃ contains three single bonds, with phosphorus in the center, and three fluorines on either side. There are three lone pairs on each fluorine atom, and one lone pair on the phosphorus atom.

Steps

By using the following steps, you can easily draw the Lewis structure of PF₃:

#1 Draw skeleton
#2 Show chemical bond
#3 Mark lone pairs
#4 Calculate formal charge and check stability (if octet is already completed on central atom)

Let’s one by one discuss each step in detail.

#1 Draw skeleton

In this step, first calculate the total number of valence electrons. And then, decide the central atom.

• Let’s calculate the total number of valence electrons

We know that… phosphorus is a group 15 element and fluorine is a group 17 element. Hence, phosphorus has five valence electrons and fluorine has seven valence electrons.

Now PF₃ has one phosphorus atom and three fluorine atoms.

So the total number of valence electrons = valence electrons of phosphorus atom + (valence electrons of fluorine atom × 3)

Therefore, the total number of valence electrons = 5 + 21 = 26

• Now decide the central atom

The atom with the least electronegative value is placed at the center. By looking at the periodic table, we get the electronegativity values for phosphorus and fluorine as follows:

Electronegativity value of phosphorus = 2.19
Electronegativity value of fluorine = 3.98

Obviously, phosphorus is less electronegative than fluorine. Hence, assume that phosphorus is the central atom.

So now, put phosphorus in the center and fluorines on either side. And draw the rough skeleton structure for the Lewis structure of PF₃ something like this:

Also read: How to draw Lewis structure of XeF₄ (4 steps)

#2 Show chemical bond

Place two electrons between the atoms to show a chemical bond. Since phosphorus is surrounded by three fluorines, use six electrons to show three chemical bonds as follows:

Also read: How to draw Lewis structure of F₂ (4 steps)

#3 Mark lone pairs

As calculated earlier, we have a total of 26 valence electrons. And in the above structure, we have already used six valence electrons. Hence, twenty valence electrons are remaining.

Two valence electrons represent one lone pair. So twenty valence electrons = ten lone pairs.

Note that phosphorus is a period 3 element, so it can keep more than 8 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.

Also, make sure that you start marking these lone pairs on outside atoms first. And then, on the central atom.

The outside atoms are fluorines, so each fluorine will get three lone pairs. And the central atom (phosphorus) will get one lone pair.

So the Lewis structure of PF₃ looks something like this:

In the above structure, you can see that the octet is completed on the central atom (phosphorus), and also on the outside atoms. Therefore, the octet rule is satisfied.

After completing the octet, one last thing we need to do is, calculate the formal charge and check the stability of the above structure.

Also read: How to draw Lewis structure of PO₄^3- (5 steps)

#4 Calculate formal charge and check stability

The following formula is used to calculate the formal charges on atoms:

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

Collect the data from the above structure and then, write it down below as follows:

• For phosphorus atom

Valence electrons = 5
Nonbonding electrons = 2
Bonding electrons = 6

Formal charge = 5 – 2 – ½ (6) = 0

• For each fluorine atom

Valence electrons = 7
Nonbonding electrons = 6
Bonding electrons = 2

Formal charge = 7 – 6 – ½ (2) = 0

Mention the formal charges of atoms on the structure. So the Lewis structure of PF₃ looks something like this:

In the above structure, you can see that the formal charges of both (phosphorus and fluorine) are zero. Therefore, this is the stable Lewis structure of PF₃.

And each horizontal line drawn in the above structure represents a pair of bonding valence electrons.

📝 Your feedback matters. Visit our contact page.

Related

• Lewis structure of XeF₄
• Lewis structure of F₂
• Lewis structure of PO₄^3-
• Lewis structure of HCl
• Lewis structure of ClO₂^–

External links

• PF3 Lewis Structure in 6 Steps (With Images) – Pediabay
• PF3 lewis structure, Molecular geometry, Bond angle, Hybridization – Topblogtenz
• PF3 Lewis Structure, Molecular Geometry, and Hybridization – Techiescientist
• How to draw PF3 Lewis Structure? – Science Education and Tutorials
• Chemical Bonding: PF3 Lewis Structure – The Geoexchange
• PF3 Lewis Structure (Phosphorus Trifluoride) – Pinterest
• What is the Lewis structure for PF3? – Homework.Study.com
• Draw the Lewis structure for PF3 – Chegg
• Compare the structures of SO3 to PF3 and explain why they have different molecular shapes? – Socratic
• Write a Lewis structure for the phosphorus trifluoride molecule, PF3 – Numerade
• What are the resonance structures of PF3? – Quora
• Why does the phosphorus trifluoride molecule have dipole moment? – Chemistry Stack Exchange
• PF3 molecular geometry – Laurence Lavelle