BrF5 Molecular Geometry - Science Education and Tutorials

Q: What is the molecular notation for BrF5 molecule?

BrF5 molecular notation is AX5N1.

Pentafluoro bromine or bromine pentafluoride(BrF5) has the composition of one bromine and five fluorine atoms. What is the molecular geometry of bromine pentafluoride?. Drawing and predicting the BrF5 molecular geometry is very easy by following the given method. Here in this post, we described step by step to construct BrF5 molecular geometry. Bromine and fluorine come from the 17th family group in the periodic table. Bromine or fluorine has seven valence electrons.

Table of Contents

Key Points To Consider When drawing The BrF5 Molecular Geometry

A three-step approach for drawing the BrF5 molecular can be used. The first step is to sketch the molecular geometry of the BrF5 molecule, to calculate the lone pairs of the electron in the central bromine atom; the second step is to calculate the BrF5 hybridization, and the third step is to give perfect notation for the BrF5 molecular geometry.

The BrF5 molecular geometry is a diagram that illustrates the number of valence electrons and bond electron pairs in the BrF5 molecule in a specific geometric manner. The geometry of the BrF5 molecule ion can then be predicted using the Valence Shell Electron Pair Repulsion Theory (VSEPR Theory) and molecular hybridization theory, which states that molecules will choose the BrF5 geometrical shape in which the electrons have from one another in the specific molecular structure.

Finally, you must add their bond polarities characteristics to compute the strength of the five Br-F bonds (dipole moment properties of the BrF5 molecular geometry). Five bromine-fluorine bonds in the bromine pentafluoride(BrF5), for example, are polarised toward the more electronegative value fluorine atoms, and because all five (Br-F) bonds have the same size and polarity, their sum is nonzero due to the BrF5 molecule’s bond dipole moment due to pulling the electron cloud to the downside in the square pyramidal geometry, and the BrF5 molecule is classified as a polar molecule.

The molecule of bromine pentafluoride(with square pyramidal shape BrF5 molecular geometry) is tilted at 90 degrees bond angle of F-Br-F. It has a difference in electronegativity values between bromine and fluorine atoms, with fluorine’s pull the electron cloud being greater than bromine’s. But bond polarity of Br-F is not canceled to each other in the square pyramidal geometry. As a result, it has a permanent dipole moment in its molecular structure. The BrF5 molecule has a dipole moment due to an unequal charge distribution of negative and positive charges.

Overview: BrF5 electron and molecular geometry

According to the VSEPR theory, the BrF5 molecule ion possesses square pyramidal molecular geometry. Because the center atom, bromine, has five Br-F bonds with the five fluorine atoms surrounding it. The F-Br-F bond angle is 90 degrees in the square pyramidal BrF5 molecular geometry. The BrF5 molecule has a square plannar geometry shape because it contains four fluorine atoms in the plan and one fluorine lie out of the plan.

There are five Br-F bonds at the BrF5 molecular geometry. After linking the five fluorine atoms and one lone pairs of electrons in the square pyramidal form, it maintains the square bipyramidal shaped structure. In the BrF5 molecular geometry, the Br-F bonds have stayed in the five terminals and one lone pair of electron on the bromine atom of the square pyramidal molecule.

The center bromine atom of BrF5 has one lone pairs of electrons, resulting in square pyramidal BrF5 electron geometry. However, the molecular geometry of BrF5 looks square pyramidal shaped and one lone pair of electron on the bromine of the BrF5 geometry. It’s the BrF5 molecule’s asymmetrical geometry. As a result, the BrF5 molecule is polar.

How to find BrF5 hybridization and molecular geometry

Calculating lone pairs of electrons on bromine in the BrF5 geometry:

1.Determine the number of lone pairs of electrons in the core bromine atom of the BrF5 Lewis structure. Because the lone pairs of electrons on the bromine atom are mostly responsible for the BrF5 molecule geometry distortion, we need to calculate out how many there are on the central bromine atom of the BrF5 Lewis structure.

Use the formula below to find the lone pair on the bromine atom of the BrF5 molecule.
L.P(Br) = V.E(Br) – N.A(Br-F)/2

Lone pair on the central bromine atom in BrF5 = L.P(Br)
The core central bromine atom’s valence electron in BrF5 = V.E(Br)
Number of Br-F bonds = N.A (Br-F)
calculation for bromine atom lone pair in BrF5 molecule.

For instance of BrF5, the central atom, bromine, has seven electrons in its outermost valence shell, five Br-F bond connections. This gives a total of five connections.

As a result of this, L.P(Br) = (7 –5)/2=1

The lone pairs of electrons in the bromine atom of the BrF5 molecule is one.

Calculating lone pairs of electrons on fluorine in the BrF5 geometry:

Finding lone pairs of electron for the terminal atom is not with the similar as the central bromine atom. We use following formula as given below

Use the formula below to find the lone pair on the fluorine atom of the BrF5 molecule.
L.P(F) = V.E(F) – N.A(Br-F)

Lone pair on the terminal fluorine atom in BrF5 = L.P(F)
Terminal fluorine atom’s valence electron in BrF5 = V.E(F)
Number of Br-F bonds = N.A ( Br-F)
calculation for fluorine atom lone pair in BrF5 molecule.

For instance of BrF5, five terminal atoms, fluorine, have seven electrons in its outermost valence shell, one Br-F bond connection. This gives a total of five Br-F bond connections. But we are considering only one connection for the calculation.

As a result of this, L.P(F) = (7 –1)=6

The lone pairs of electrons in the fluorine atom of the BrF5 molecule are six. Five fluorine atoms are connected with the central bromine atom.

In the BrF5 electron geometry structure, the lone pair on the central bromine atom is one, lone pairs of electrons in the fluorine atom have six. Five fluorine atoms have 30 lone pairs of electrons.

It means there are one lone pair of electrons in the core bromine atom. One lone pair of electrons on the central bromine atom is responsible for the square pyramidal nature of BrF5 molecular geometry. But in the structure fluorine atoms are polarised sidewise in their geometry.

The one lone pair of electrons are placed at another side of the BrF5 geometry. Because the bromine atom is a lower electronegative value as compared with other atoms in the BrF5 molecule. Five fluorine atoms are polarized towards the sidewise in the BrF5 structure.

But in reality, the BrF5 has one lone pair of electrons in its structure. This makes the BrF5 more irregular structure of the molecule. Because there is electric repulsion between bond pairs and lone pairs. But some sort of interaction is there between fluorine lone pairs and bond pairs. But it is negligible.

Calculate the number of molecular hybridizations of the BrF5 molecule

What is BrF5 hybridization? This is a very fundamental question in the field of molecular chemistry. All the molecules are made of atoms. In chemistry, atoms are the fundamental particles. There are four different types of orbitals in chemistry. They are named s, p, d, and f orbitals.

The entire periodic table arrangement is based on these orbital theories. Atoms in the periodic table are classified as follows:

s- block elements
p- block elements
d-block elements
f-block elements
Atoms are classified in the periodic table

BrF5 molecule is made of one bromine, five fluorine atoms. The fluorine and bromine atoms have s and p orbitals. Fluorine comes as the first element from the halogen family in the periodic table. The bromine atom also belongs to the same family group. But it falls as the third element in the periodic table.

When these atoms combine to form the BrF5 molecule, its atomic orbitals mixed and form unique molecular orbitals due to hybridization.

How do you find the BrF5 molecule’s hybridization? We must now determine the molecular hybridization number of BrF5.

The formula of BrF5 molecular hybridization is as follows:
No. Hyb of BrF5= N.A(Br-F bonds) + L.P(Br)
No. Hy of BrF5 = the number of hybridizations of BrF5
Number of Br-F bonds = N.A (Br-F bonds)
Lone pair on the central bromine atom = L.P(Br)
Calculation for hybridization number for BrF5 molecule

In the BrF5 molecule, bromine is a core central atom with five fluorine atoms connected to it. It has one lone pair of electrons on bromine. The number of BrF5 hybridizations (No. Hyb of BrF5) can then be estimated using the formula below.

No. Hyb of BrF5= 5+1=6

The BrF5 molecule ion hybridization is six. The bromine and fluorine atoms have s,p and d orbitals. The sp3d2 hybridization of the BrF5 molecule is formed when one S orbital, three p orbitals, and two d orbital join together to form the BrF5 molecular orbital.

Molecular Geometry Notation for BrF5 Molecule :

Determine the form of BrF5 molecular geometry using VSEPR theory. The AXN technique is commonly used when the VSEPR theory is used to calculate the shape of the BrF5 molecule.

The AXN notation of BrF5 molecule is as follows:
The central bromine atom in the BrF5 molecule is denoted by the letter A.
The bound pairs (five Br-F bonds) of electrons to the core bromine atom are represented by X.
The lone pairs of electrons on the central bromine atom are denoted by the letter N.
Notation for BrF5 molecular geometry

We know that bromine is the core atom, with five electron pairs bound (five Br-F) and one lone pair of electrons. The general molecular geometry formula for BrF5 is AX5N1.

According to the VSEPR theory, if the BrF5 molecule ion has an AX5N1 generic formula, the molecular geometry and electron geometry will both square pyramidal forms.

Name of Molecule	Bromine pentafluoride
Chemical molecular formula	BrF5
Molecular geometry of BrF5	Square pyramidal
Electron geometry of BrF5	Square pyramidal
Hybridization of BrF5	sp3d2
Bond angle (F-Br-F)	90º degree
Total Valence electron for BrF5	42
The formal charge of BrF5 on bromine	0

Summary:

In this post, we discussed the method to construct BrF5 molecular geometry, the method to find the lone pairs of electrons in the central bromine atom, BrF5 hybridization, and BrF5 molecular notation. Need to remember that, if you follow the above-said method, you can construct the BrF5 molecular structure very easily.