Lewis structure of PBr5

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The Lewis structure of PBr₅ contains five single bonds, with phosphorus in the center, and five bromines on either side. There are three lone pairs on each bromine 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 PBr₅.

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

Now PBr₅ has one phosphorus atom and five bromine atoms.

So the total number of valence electrons = valence electrons of phosphorus atom + (valence electrons of bromine 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 bromine as follows:

Electronegativity value of phosphorus = 2.19
Electronegativity value of bromine = 2.96

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

So now, put phosphorus in the center and bromines on either side. And draw the rough skeleton structure for the Lewis structure of PBr₅ something like this:

Also read: How to draw Lewis structure of OCS (5 steps)

#2 Show chemical bond

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

Also read: How to draw Lewis structure of H₃O⁺ (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 phosphorus is a period 3 element, so it can keep more than 8 electrons in its last shell. And bromine is a period 4 element, so it can 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 bromines, so each bromine 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 PBr₅ 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 AsH₃ (4 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 bromine 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 PBr₅ looks something like this:

In the above structure, you can see that the formal charges of both (phosphorus and bromine) are zero. Therefore, this is the stable Lewis structure of PBr₅.

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

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Related

• Lewis structure of OCS
• Lewis structure of H₃O⁺
• Lewis structure of AsH₃
• Lewis structure of Br₃^–
• Lewis structure of SeF₆

External links

• PBr5 lewis structure, molecular geometry, polar or nonpolar, hybridization – Topblogtenz
• PBr5 Lewis Structure in 5 Steps (With Images) – Pediabay
• PBr5 Molecular Geometry, Lewis structure, Shape, Bond Angle, And More – Geometry of Molecules
• PBr5 Lewis Structure, Molecular Geometry, Hybridization, and Polarity – Techiescientist
• What is the molecular geometry of PBr5? Draw its VSEPR and Lewis structure – Socratic
• What is PBr5 Lewis structure? – Homework.Study.com
• Drawing the Lewis Structure for PBr5 – The Geoexchange
• PBr5 – CHEMISTRY COMMUNITY – Laurence Lavelle
• How do I draw a Lewis Structure for PBr5? – Chegg
• What is the molecular geometry of PBr5? Draw its VSEPR and Lewis structure – Brainly
• Draw the Lewis structure of PBr5 – OneClass