Lewis structure of PBr3 - How to draw Lewis structure of PBr3, Polarity, Molecular Geometry and Hybridization along with FAQs (2024)

In the trigonal pyramidal molecular geometry, the central atom is phosphorus, which is bordered on three terminals by bromine atoms (in trigonal pyramidal geometry), and one lone pair on the central phosphorus atom. Phosphorus has five outermost valence electrons, indicating that it has five electrons in its outermost shell, whereas bromine has seven outermost valence electrons. Three and one valence electrons are required on each of the phosphorus and bromine atoms outermost shells, respectively, to complete the octet.

Table of Contents

  • How to draw the Lewis Structure of PBr3?
  • Molecular Geometry of PBr3
  • Hybridization of PBr3
  • Polarity of PBr3
  • Frequently Asked Questions – FAQs

How to Draw the Lewis Structure of PBr3

Lewis dot structures, also known as Lewis structures, are diagrams that enable us to understand the bonding of atoms as well as the lone pairs present in a molecule. The valence electrons of atoms form bonds, which are represented by straight lines. Each bond absorbs two valence electrons, and the excess electrons are represented as lone pairs.

Bonding pairs of electrons participate in bond formation, whereas lone pairs or nonbonding pairs of electrons do not participate in bond formation.

Steps to draw Lewis structure ofPBr3,

1. Determine the total number of electrons in the valence (outer shell).

In the periodic table, phosphorus is in the 15th group, and bromine is in the 17th.

As a result, the valence electron of-

Phosphorus = 5

Bromine = 7

∴ Total available valence electrons = 5 + 3(7) = 26.

2. Determine the total number of electron pairs that exist as lone pairs and bonds.

Total electron pairs are calculated by dividing the total valence electron count by two. In the valence shells of the PBr3 molecule, there are 13 pairs of electrons.

3. Make a skeleton structure for the molecule by arranging the atoms around a central atom.

The central atom will be phosphorus as it is the least electronegative among phosphorus and bromine. A single bond will connect each atom to the central atom (one electron pair).

Lewis structure of PBr3 - How to draw Lewis structure of PBr3, Polarity, Molecular Geometry and Hybridization along with FAQs (1)

4. Mark atom with lone pairs.

A total of 13 electron pairs should be present as lone pairs and bonds in valence shells.

  • There are already three bonds. As a result, there are ten more lone pairs to mark on Phosphorous and Bromine atoms.
  • First, mark any remaining lone pairs on the outside atoms. As a result, the nine remaining electron pairs are marked.Lewis structure of PBr3 - How to draw Lewis structure of PBr3, Polarity, Molecular Geometry and Hybridization along with FAQs (2)
  • The remaining one electron pair will be marked on the central atom.

Lewis structure of PBr3 - How to draw Lewis structure of PBr3, Polarity, Molecular Geometry and Hybridization along with FAQs (3)

5. If there are charges on atoms, mark them.

There are no charges present on any of the atoms.

6. To obtain the best Lewis structure, minimise charges on atoms by converting lonepairs to bonds.

Since there are no charges on atoms, there is no need to reduce charges as part of the process of drawing the best Lewis structure. We already have the best Lewis structure for PBr3.

7. Check the stability of the structure

It can be checked by using the formula-

Formal charge = Valence Electrons – Unbonded Electrons – ½ Bonded Electrons

Formula AppliedValence electrons = 5

Lone pair electrons = 2

Shared pair electrons (3 single bonds) = 6

Valence electrons = 7

Lone pair electrons = 6

Shared pair electrons (1 single bond) = 2

Formal Charge(5 – 2 – 6/2) = 0(7 – 6 –2/2) = 0

Since the overall formal charge is zero, the above Lewis structure of PBr3 is most appropriate, reliable, and stable in nature.

Molecular Geometry of PBr3

There are three bonding pairs of electrons and one lone pair of electrons in PBr3. The molecule will form a geometry in such a way that the repulsive forces are minimised.

Phosphorus is the central atom in PBr3, and three bromine atoms form bonds with it. There is one lone pair of electrons. As a result, it has a tetrahedral geometry. Hence, the required shape is trigonal bipyramidal.

Bond angles of 109.5° are common in molecules with tetrahedral electron geometry and one central atom forming bonds with three atoms. However, the atom arrangement is asymmetrical here, and there is a single pair of electrons on the central atom; the bond angle will not be exactly the same, but it will be around 109.5°.

Lewis structure of PBr3 - How to draw Lewis structure of PBr3, Polarity, Molecular Geometry and Hybridization along with FAQs (4)

Hybridization of PBr3

Phosphorus Tribromide contains three bonding pairs and one nonbonding or lone pair of electrons.

To accommodate all four pairs of electrons, the central atom forms four hybridised orbitals. Since four hybrid orbitals are formed, its hybridization is sp3.

Polarity of PBr3

Phosphorus has an electronegativity of 2.19, while Bromine has an electronegativity of 2.96. The disparity in electronegativities is quite large. As a result, there will be a dipole moment between the atoms of phosphorus and bromine. Since the bromine atom is more electronegative, the direction of this dipole moment will be towards it.

Since there are three Bromine atoms in this molecule, dipole moments do not cancel each other out, and the molecule has a net dipole moment. As a result, it is a polar molecule with a partially positively charged region surrounding the Phosphorus atom and a partially negatively charged region surrounding the Bromine atoms.

Frequently Asked Questions on Lewis Structure of PBr3


How many valence electrons are there in PBr3 Lewis structure?

There are a total of 26 valence electrons, and the total number of electron pairs will be 13. Out of these thirteen bonds, three bonds form a single bond and the rest 10 form lone pairs.


What is the molecular geometry of PBr3?

The molecular geometry of PBr3 according to VSEPR theory is tetrahedral and the shape of the molecule is trigonal bipyramidal.


What is the polarity of the PBr3 molecule?

Due to the unequal charge distribution of negative and positive charges, the PBr3 molecule has a nonzero dipole moment. In the PBr3 molecule, the bromine atom has a more electronegative value than the phosphorus atom. In the ground state energy state, the PBr3 molecule has a net dipole moment of 0.66D making it polar in nature.


How many lone pairs are present in the molecule of PBr3?

In the lewis structure of PBr3, there are ten lone pairs, three on each of the bromine atoms and one on the central atom that is phosphorus.


What is the hybridization of PBr3?

The hybridization of PBr3 is sp3.

Lewis structure of PBr3 - How to draw Lewis structure of PBr3, Polarity, Molecular Geometry and Hybridization along with FAQs (2024)
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