Lewis structure of PCl5

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The Lewis structure of PCl₅ contains five single bonds, with phosphorus in the center, and five chlorines on either side. There are three lone pairs on each chlorine atom, and the phosphorus atom does not have any lone pair.

Steps

By using the following steps, you can easily draw the Lewis structure of PCl₅:

#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 chlorine is a group 17 element. Hence, phosphorus has five valence electrons and chlorine has seven valence electrons.

Now PCl₅ has one phosphorus atom and five chlorine atoms.

So the total number of valence electrons = valence electrons of phosphorus atom + (valence electrons of chlorine atom × 5)

Therefore, the total number of valence electrons = 5 + 35 = 40

• 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 chlorine as follows:

Electronegativity value of phosphorus = 2.19
Electronegativity value of chlorine = 3.16

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

So now, put phosphorus in the center and chlorines on either side. And draw the rough skeleton structure for the Lewis structure of PCl₅ something like this:

Also read: How to draw Lewis structure of C₂H₆ (3 steps)

#2 Show chemical bond

Place two electrons between the atoms to show a chemical bond. Since phosphorus is surrounded by five chlorines, use ten electrons to show five chemical bonds as follows:

Also read: How to draw Lewis structure of CHCl₃ (4 steps)

#3 Mark lone pairs

As calculated earlier, we have a total of 40 valence electrons. And in the above structure, we have already used ten valence electrons. Hence, thirty valence electrons are remaining.

Two valence electrons represent one lone pair. So thirty valence electrons = fifteen lone pairs.

Note that both (phosphorus and chlorine) are the period 3 elements, so they can keep more than 8 electrons in their 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 not get any lone pair, because all fifteen lone pairs are used.

So the Lewis structure of PCl₅ 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 H₂ (3 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 = 0
Bonding electrons = 10

Formal charge = 5 – 0 – ½ (10) = 0

• For each chlorine 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 PCl₅ looks something like this:

In the above structure, you can see that the formal charges of both (phosphorus and chlorine) are zero. Therefore, this is the stable Lewis structure of PCl₅.

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

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Related

• Lewis structure of C₂H₆
• Lewis structure of CHCl₃
• Lewis structure of H₂
• Lewis structure of SF₂
• Lewis structure of N₃^–

External links

• Drawing the Lewis Structure for PCl5 – The University of Maryland
• PCl5 Lewis Structure in 5 Steps (With Images) – Pediabay
• PCl5 (Phosphorus pentachloride) Lewis Structure – Chemistry School
• PCl5 lewis structure, molecular geometry, bond angle, hybridization – Topblogtenz
• PCl5 Lewis Structure, Molecular Geometry, Hybridization, and MO Diagram – Techiescientist
• PCl5 Lewis Structure, Molecular Structure, Hybridization, Bond Angle, and Shape – Geometry of Molecules
• What is the Lewis structure of PCl5? – Quora
• Lewis Structure of PCl5 [with free study guide and video] – AceOrganicChem
• Phosphorus Pentachloride, PCl5 Molecular Geometry & Polarity – Tutor-Homework.com
• Drawing the Lewis Structure for PCl5 – The Geoexchange
• Lewis Dot of Phosphorus Pentachloride PCl5 – Kent’s Chemistry
• Give the Lewis structure for PCl5 – Homework.Study.com
• Draw the Lewis structure for PCl5 – Chegg
• Phosphorus pentachloride (PCl5) as exception to octet rule – Laurence Lavelle
• What is the formal charge on P in PCl5? – Studocu
• How do you draw the Lewis structure of phosphorus pentachloride? – Socratic
• PCl5 Geometry and Hybridization – Chemistry Steps
• Draw the Lewis structure of PCl5 • What is the shape of this molecule? – Numerade
• Draw the Lewis structure of phosphorus pentachloride (PCl5) – OneClass
• Draw the Lewis structure of PCl5 and determine its molecular geometry – Quizlet