PBr5 lewis Structure: Drawings, Hybridization, Shape, Charges, Pair And Detailed Facts

In this article, we are going to analyze PBr5 lewis structure and various facts about it.

PBr5 or phosphorus pentabromide is a compound of phosphorus and bromine which is yellow colored (solid) in appearance. It has a got huge application in organic chemistry. So we will study the bonding in PBr5 by understanding the PBr5 lewis structure.

Some facts about phosphorus pentabromide

This compound has a molar mass of around 430.49 g/mol. The observed density of PBr5 is 3.61 g/cm3. It melting point is somewhere around 100 degrees Celsius and boils at a temperature of 106 degrees Celsius. Talking about its solubility it is observed to be soluble in carbon tetrachloride, carbon disulphide. But it decomposes in an organic solvent like ethanol.

How to draw lewis structure for PBr5

By using lewis concept of bonding we can clearly understand about how the bonding occurs in a molecule. How many electrons are involved and are bonding electrons. Also tells us about the electrons that are of nonbonding type.

Image credit: Wikipedia

So in this method, we first calculate or find out about the number of valence electrons present in the molecule that is being for study. So in this molecule of PBr5, there are five bromine atoms present and one atom of phosphorus is present. Hence total atoms involved in the molecule structure are 6. So the number of valence electrons in bromine atom is 7, meaning it has the potential to gain one electron or share one electron and complete its octet. But the total number of bromine atoms involved in the structure of the molecule is equal to 5, so the total number of valence electrons that is contributed by it will be 7×5=35 electrons.

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And in the P element there exist 5 valence electrons. Since there is only one atom of this element, the number of valence electrons contribution will be 5. And the total number that valence electrons are present in the molecule is equal to 40. So the phosphorus element atom tends to share one electron pair each with five atoms of bromine element. In this way the valency of all the elements in the molecule structure is satisfied. Remember one important point the atom in the molecule which is having less electronegativity when compared to the other atom in the molecule will be preferred to be kept in the middle of the molecule.

PBr5 lewis structure shape

The coordination number that is possible in the molecule of PBr5 is equivalent to 5.

Meaning it has the potential to form 5 more bonds. As we have seen above the details regarding bond formation and its capability of forming bond, we can now say that PBr5 molecule has a trigonal bipyramidal shape. In the geometry of trigonal bipyramidal what happens is the atom having less electronegativity then the other present atoms is kept at the middle/center of the molecule.

Image credit: Wikipedia

And 5 atoms can attach to it. So in this molecule of phosphorus pentabromide, central atom P is surrounded or forms a bond with 5 atoms of bromine.

PBr5 lewis structure formal charge

In the concept of formal charge it is assumed first itself that the electrons that are being shared in the process of bonding, they are shared in an equal manner. Below is the formula that will tell more about the concept of formal charge:

Where V is the number of valence electrons in the molecule that we are studying.

N is equal to the electrons that are not bonded meaning the non-binding type of electrons.

B indicates the total of all the electrons that are actively participating in the bonding.

The formal charge in PBr5 is zero.

PBr5 lewis structure lone pairs

When the bonding process is occurring in a molecule not necessarily all the electrons will actively participate in the process.

Some electrons are left out, meaning they are not shared and this electrons pair is referred or known as lone pair. In the molecule of PBr5, there are total 6 atoms having 40 valence electrons. This valence electrons are shared between the atoms forming single bonds.

As all the electrons are participating in bonding there is no lone pair in this molecule of PBr5.

PBr5 hybridization

The term hybridization symbolizes or means that there is mixing of orbitals of atoms to form new hybrid orbitals. And this new orbitals (hybrid) are going to have different shape, energy meaning its properties will be different.

The below-discussed formula can be utilized to predict hybridization in the PBr5 molecule:



V will be the central atoms total number of valence electrons

N will be the monovalent number of atoms attached or bonding to the center atom

C will be the charge induced by cation

A will be the charge induced by the anion

Coming to hybridization in the molecule of PBr5:

According to the formula, the valence electrons of the central atom in the molecule is equivalent to 5. Monovalent number of atoms will be 5 and the anion and cation charge will be equal to zero.

Substituting all the values in the above discussed formula what we get is 5. So what it means now is the first electron (valence) will be in the s orbital. The other 3 will be in the orbitals Px, Py and Pz. The remaining one will stay with orbital dx. Hence the hybridization in phosphorus pentabromide will be sp3d.

PBr5 lewis structure resonance structure

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PBr5 lewis structure octet rule

So taking into account the octet rule concept what we understand is that the atoms last shell or outer shell wants to have a complete octet. So atoms share electrons and achieve this. In the molecule of PBr5 phosphorus and bromine share electrons according to their valency and complete their octet.

PBr5 polar or nonpolar

Phosphorus pentabromide is seen to be nonpolar as the electrons (valence) are arranged in a symmetrical manner. There is no chance for dipole moment. Hence the molecule will be nonpolar.

PBr5 lewis structure bond angle

The angle between (axial & equatorial) is 90 degrees. And the angle between electron pairs that are bonded is 120 degrees.

PBr5 uses

  • It is used in the conversion of alcohols to bromide.
  • It is used in preparation of nanowires of indium phosphide.

Also, please click to know about SECL4 Lewis Structure and  SeF6 Lewis Structure.

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