The **Lewis structure of PBr _{3}** contains three single bonds, with phosphorus in the center, and three bromines on either side. There are three lone pairs on each bromine atom, and one lone pair on the phosphorus atom.

## Steps

By using the following steps, you can easily draw the Lewis structure of PBr_{3}.

#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 PBr_{3} has one phosphorus atom and three bromine atoms.

So the total number of valence electrons = valence electrons of phosphorus atom + (valence electrons of bromine 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 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 PBr_{3} something like this:

**Also read:** How to draw Lewis structure of CH_{3}Br (4 steps)

### #2 Show chemical bond

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

**Also read:** How to draw Lewis structure of XeO_{3} (5 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 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 get one lone pair.

So the Lewis structure of PBr_{3} 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 C_{3}H_{6} (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 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 PBr_{3} 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 PBr**** _{3}**.

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

## Related

- Lewis structure of CH
_{3}Br - Lewis structure of XeO
_{3} - Lewis structure of C
_{3}H_{6} - Lewis structure of ICl
_{5} - Lewis structure of C
_{6}H_{6}

## External links

- Drawing the Lewis Structure for PBr3 – The Geoexchange
- PBr3 Lewis Structure, Molecular Geometry, Hybridization and Polarity – Geometry of Molecules
- PBr3 lewis structure, molecular geometry, polar or nonpolar, bond angle – Topblogtenz
- PBr3 Lewis Structure in 6 Steps (With Images) – Pediabay
- What is the Lewis structure of PBR3? How is it determined? – Quora
- PBr3 Lewis Structure (Phosphorus Tribromide) – Pinterest
- PBr3 Lewis Structure, Molecular Geometry, Polarity, and Hybridization – Techiescientist
- What is the Lewis structure for PBr3? – Homework.Study.com
- How to draw PBr3 Lewis Structure? – Science Education and Tutorials
- What is the Lewis structure of PBr3? (Assign lone pairs, and radical electrons where appropriate – Chegg
- Draw the Lewis Dot structure for PBr3 – Bartleby
- draw the lewis structure of pbr3. include all the lone pairs – Brainly

Deep

Rootmemory.com was founded by Deep Rana, who is a mechanical engineer by profession and a blogger by passion. He has a good conceptual knowledge on different educational topics and he provides the same on this website. He loves to learn something new everyday and believes that the best utilization of free time is developing a new skill.