Molecular Geometry, Hybridization, and Polarity of PBr5 Lewis Structure

Phosphorous Pentabromide, or PBr5, is a chemical made up of 5 Bromine molecules and 1 Phosphorus molecule. It seems to be a crystalline yellow solid. In the solid state, PBr5 has the structure PBr4+ Br, but in the vapour phase, it dissociates to form PBr3Br2.

The chemical is corrosive in nature and has a molecular weight of 430.49 g/mol. Because this chemical is highly irritating to human skin and eyes, it is stored and shipped in sealed containers.

PBr5 is commonly used to create other chemicals and compounds.

PBr5 has a melting point of 100 °C (dec.) and a boiling point of 106 °C (dec.).

The interaction between PBr5 and water produces the corrosive gas Hydrogen Bromide. When PBr5 reacts with damp air, the same thing happens.

Drawing a Lewis Structure

To learn more about a compound’s qualities, you must first understand its Lewis structure.

The Lewis structure is merely a representation of how electrons engage in the bond creation that results in the synthesis of a specific molecule.

In any chemical, there are two sorts of electrons that make up the bond formation. These are the bonding pairs of electrons that help establish the bond. Non-bonding electrons, often known as lone electrons, do not form any bonds.

Valence electrons are the total of these bonding and nonbonding electrons.

The bonds are represented by a single straight line, and the lone electrons are represented by dots. The octet rule is followed in a Lewis structure, which states that any molecule with 8 electrons in its outer shell is stable.

Let’s look at how to draw PBr5’s Lewis structure.

Lewis Structure of PBr5

The Lewis Structure of PBr5 is explained in the following section.

There is one core atom in every molecule to which other atoms are connected.

Phosphorous is the core atom in this structure. A single connection is formed between this atom and the nearby Bromine atoms, implying that two electrons are shared between these atoms.

Lone pairs, which are depicted by two dots, are the remaining electrons in the atoms.

Let’s take a mathematical look at this topic.

First and foremost, you must add up all of these atoms’ electrons.

Here,

Phosphorus has 5 electrons in its valence shell.

Br (Bromine) has seven electrons in its valence shell.

The Br atom has a valency of 5.

As a result, Br’s total Valence electrons are 7*5, or 35 Valence electrons.

As a result, the total number of Valence electrons is 35+5=40 Valence electrons.

The centre atom in this structure is Phosphorus, which connects with the other 5 Bromine molecules.

Phosphorous’ five electrons form a connection with one of each valence electron of Bromine. When all of the core atom’s electrons have been consumed, there are no lone electrons left with Phosphorous. Other Bromine atoms, however, have lone electrons.

5*6=30 is the total number of lone electrons in PBr5.

Take a look at the diagram below to visualise all of these theories.

Let’s look at the hybridization of PBr5 now that we’ve seen the Lewis structure.

Hybridization of PBr5

Do you understand what hybridization is in general before continuing on to the hybridization of PBr5? If not, read the following statement to gain a better understanding.

“Hybridization occurs when atomic orbitals merge to create or generate new hybridised orbitals. The molecule shape and bonding characteristics are changed throughout this process. Always keep in mind that mixing occurs only between orbitals with the same energy level.”

Let’s decode the hybridization of PBr5 now that you’ve learned the basics of hybridization.

A simple formula is used to calculate hybridization:

½ [ V + M – C + A ]

Where,

The number of valence electrons in the centre atom is denoted by the letter V.

N is the number of monovalent atoms that are bonded to the centre atom.

The charge of a cation is denoted by the letter C.

A is the anion’s charge.

We can swap numbers in the preceding equation to acquire the required results when calculating the hybridization of PBr5.

Here,

V is equal to 5.

Number of participants: 5

0 = C

0 = A

As a result, Hybridization = 12 [5 + 5 – 0 + 0] = 5 is obtained.

In the s orbital, the initial valence electron is placed.

Px, Py, and Pz orbitals can house the following three valence electrons.

There is only one valence electron left. As a result, it is assigned to the dx orbital.

As a result, PBr5 hybridization is sp3d.

Aside from that, the diagram below can help you understand how sp3d hybridization is accomplished.

You can grasp the orbitals better and more clearly if you use a graphical representation.

Some angles can be seen forming in the diagram above. Bond angles are what they’re called. Bond angles are simple to locate.

There are five pairs of bound electrons in total, as you can see.

The equatorial axis is perpendicular to two of these five pairs. These two pairs are referred to as axial pairs.

The equatorial axis is shared by the other three pairs.

The axial and equatorial lines form a 90-degree angle.

And there’s a 120-degree angle between the three pairs of linked electrons.

The molecular geometry of PBr5 is next. Let’s have a look at it as a group.

Molecular Geometry of PBr5

In general, a compound’s Lewis structure may simply explain its molecular geometry.

In the instance of PBr5, however, the molecular geometry can be better explained using the VESPER hypothesis.

VESPER stands for Valence Shell Electron Pair Repulsion Theory in general.

The steric number and coordination number of the atoms are used in VESPER theory to determine the geometry of the compound.

Let’s start with an explanation of what steric number and coordination number signify.

The steric number is determined by the number of lone pairs, atoms, and groups that surround the centre atom.

The steric number in the case of PBr5 is 5.

The coordination number is the number of ions, atoms, or molecules bound to a central atom in any molecule or crystal.

Because the core atom P is linked to five Br atoms in PBr5, the coordination number is five.

Because these 5 pairs of valence electrons can produce repulsion, the electrons can be dispersed over space to achieve stability.

PBr5 has a trigonal bipyramid structure due to this dispersion.

The geometry of the PBr5 molecule is depicted in the diagram below.

PBr5’s polarity

The question now is: what is the polarity of PBr5?

Because of the arrangement of atoms in this molecule, PBr5 is non-polar. In Pbr5, the valence pairs are symmetrically organised.

The dipole moment is zero when the bonds are organised symmetrically, making the compound non-polar.

Now that we’ve covered the basics of PBr5, let’s look at what a Lewis structure is and how to draw one for the PBr5 compound.

PBr5 is used in a variety of ways.

Here are a few of PBr5’s most beneficial applications to be aware of:

To convert alcohol to bromides, PBr5 is employed.

It’s used to remove the bromination from ketones.

Indium phosphide nanowires can also be made with PBr5.

Putting it all together in a nutshell

Let us review what we’ve learned about PBr5 to bring our study of this molecule to a close. PBr5 has a valence electron count of 40.

According to the VESPER theory, PBr5 exhibits trigonal bipyramidal geometry after sp3d hybridization. Because of the symmetric arrangement of bound and lone pairs of electrons, the molecule is nonpolar.

We hope you found this post informative and that you now understand the basic structure and geometry of PBr5. Please feel free to contact our staff for clarifications if you have any questions about this topic.

Thank you for taking the time to read this.

Read more: Molecular Geometry, Hybridization, and Polarity of NOCl Lewis Structure

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.

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