BrF3, known as Bromine Trifluoride, is a fuming liquid consisting of inter-halogen combinations and bearing a pungent smell.
Having a straw i.e, colorless to yellow appearance, this chemical compound has several applications but also comes with a number of limitations and hazard issues.
Here’s how we can synthesize or prepare the compound BrF3 :
Since BrF3 consists of three fluorine molecules, this is a strong agent of fluorination. Also, this bearing both Br and F can give rise to HBr and HF acids.
Highly soluble in sulfuric acid and acting as fluorine donors are some of the properties of bromine trifluoride.
Not only this, it has its application as an oxidizer in rocket propellants, as well as, acts as powerful inorganic solvents and even in manufacturing of uranium combined halogens for nuclear fuels.
The vast branches of usage do not negate the fact that BrF3 is highly reactive in water and quite toxic resulting in different human illnesses ranging from skin burns to eye ulcers and irritation in the respiratory system.
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Chemical Bonding in BrF3
The key to learning any compound thoroughly from the core is via its bonding nature and strength. If we get to learn why certain atoms come close and combine to form complex chemical structures and the different types of bonds that they form to achieve this complexity and formation of bigger compounds is to understand the chemical bonding of any given molecule or ion.
We have different types of chemical bonds: ionic, covalent, metallic, hydrogen, and so on. We have different bond strengths and reactivities in several existing molecules.
We have seen unique arrangements resulting in diverse chemical compositions which exhibit contrasting or like chemical and physical properties.
BrF3 being an interhalogen compound has its individualistic characteristics and reactive strength owing to its unique bonding nature.
Here, in this article, we will try to establish some knowledge about the bonding occurring inside a Bromine Trifluoride molecule.
To do that, we will have to first learn the steps to sketch a perfect Lewis Structure for BrF3.
BrF3 Lewis Structure
Definition
When a molecule is formed, it consists of several atomic elements, either the same or different that come together and form single or multiple bonds to form the above-mentioned molecular structure.
Lewis Structure is the diagrammatic form given to the skeleton of any molecular composition or ion formed with the help of the constituent elements, the valence electron concept, and the bond formation.
This is a two-dimensional structural representation and gives us a brief yet clear idea about the internal whereabouts of a molecule.
Steps to form BrF3 Lewis Structure
Step 1: How many valence electrons does a molecule of BrF3 contain? Br and F are both halogens belonging to group 7 in the periodic table.
Therefore, both of these elements will have a valency of 7. The total number of valence electrons in BrF3
= 7 + 7*3
= 7 + 21
= 28.
Step 2: Now, which is going to act as the central atom?
As per the common rule, we keep the least electronegative element in the center.
The electronegativity chart says that Bromine has an electronegativity value of 2.96 whereas F has the value of 3.98.
Hence, we keep the only Br atom in the center flanked by the F atoms.
Step 3: Now, we will put the 28 valence electrons around the atoms to achieve octet fulfillment.
We have achieved our octet configuration for every atom here. Br and the three F atoms each have eight electrons surrounding them as valence electrons.
Step 4:There will be a single bond formation with bromine and each of the fluorine atoms. But, if we count the total number, it counts up to 26 and not 28.
Step 5: What should we do now?
We will put the electron pair on top of Bromine. This is an exception to the octet rule where Br will have ten valence electrons surrounding itself.
Step 6: To check whether this is the most suitable Lewis Structure formation of BrF3, we will have to understand another concept: Formal Charge.
Formal Charge is the charge given to constituent atoms inside a chemical molecule where the bonding is shared equally among all the atoms present.
This is how we calculate the formal charge.
In Lewis Structure formation, we have to check whether all the atoms have their least possible formal charge values.
Let us calculate for BrF3:
F: Formal Charge= 7- 0.5* 2 -6 = 0
Br: Formal Charge= 7- 0.5*6 -4 = 0
We can see that the three F atoms and the single Br atom all have their formal charge value to be 0. Therefore, we can conclude that we have already got our most appropriate LS diagram.
BrF3 Molecular Geometry
What is Molecular Geometry?
Molecular geometry is an essential concept based on VSEPR theory that helps us determine the 3D structure of a molecule.
VSEPR theory stands for Valence Shell Electron Pair Repulsion Theory.
This model that we use to find out the exact molecular shape of any given composition is a theoretical approach that depends on the repulsive nature of like charges of electron clouds.
Do you know that every valence electron surrounding an atomic nucleus inside a molecule has a role to play to minimize the repulsion that they experience so that the balanced geometry can be attained?
It does not matter whether the electron is sharing a single bond, a double or triple bond, or even belongs to lone pairs. However, the repulsion strength varies- the least experienced between bonded pairs and the maximum between lone pairs.
Let us now use this concept and find out the molecular geometry of BrF3.
BrF3 Molecular Geometry
Let us have a look at the Lewis Structure again.
Br is the central atom. We have three Fluorine atoms surrounding the central Br atom, therefore three bond pairs.
We have two lone pairs on the Bromine atom, an exception to the octet rule.
The steric number is an important term here, which we need to find out for any VSEPR calculation.
Steric Number stands for the sum of the number of bonded electrons and the lone pair on the central atom.
steric number in BrF3 = 3+2 = 5
Let us now look at the following chart:
If we look closely, we can point out that the VSEPR geometry for Bromine Trifluoride is T-shaped.
If we look at the alphabet T which this molecule resembles, we can infer that the angle has to be 90 degrees.
But here, the bond angles are reduced to around 86 degrees, which is <90 degrees.
This happens due to the high electronegativity power of halogen F and also due to the influence of two lone pairs that push the bonds somewhat to make the angle less than 90 degrees.
Therefore, we have a bent T-shape for the BrF3 molecule.
BrF3 Polarity
The BrF3 molecule is considered a non-polar molecule.
As there is a high difference between the electronegativity of Br and F atoms. The charges are distributed non-uniformly across the entire molecule.
The shape of the BrF3 is asymmetrical due to lone pairs present on the Bromine atom that is also a major reason for the non-uniform charge distribution.
The net dipole moment of such non-polar molecules is non-zero.
For detailed information, you must read out a prewritten article on the polarity of BrF3.
BrF3 Hybridization
We have not properly deciphered the bonding nature of any given molecular compound unless and until we have worked on the hybridization.
Brief Intro
Orbital hybridization is an inseparable concept in the chapter on chemical bonding where we deal with the several atomic orbitals like s, p, d, and f and how they combine and fuse to give rise to several hybridized orbitals to form bonds.
We have several levels of hybridization according to the combination type. We have sp, sp2, sp3, sp3d, and so on.
What is the Hybridization for Bromine in BrF3?
The BrF3 molecule undergoes sp3d hybridization.
Let us look at the electronic configurations of F and Br.
F: 1s2 2s2 2p5
F: [He] 2s2 2p5
Br: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5
Br: [Ar] 4s2 3d10 4p5
When we are looking at the bond formation of Br with each of the fluorine atoms, the paired electrons will shift to fill up the 4d orbital.
Thus we have the one s orbital, px, py, and pz orbitals and one d orbital( dxy for example)
Therefore, we will have sp3d hybridization and this process also depends on the steric number, one we have already discussed in the molecular geometry section.
Molecular Orbital Diagram
Molecular Orbital Theory, which is used to sketch the MO diagram of any given molecule, is a complex yet important concept of chemical bonding.
In quantum mechanics, MO theory deals with spatial and energetic properties of electrons and talks about the LCAO (Linear Combination of Atomic Orbitals) to form MO( Molecular Orbitals).
This has several types of orbitals to work with: bonding, anti-bonding, and non-bonding. Other than that we also see the concepts of sigma, pi, delta, HUMO, and LUMO.
The above-mentioned diagram shows the MO structure of BF3 (Boron Trifluoride) for your reference.
Conclusion
In this article, we have discussed the chemical bonding fundamentals of the molecule of BrF3. We have dealt with Lewis Structure, Molecular Geometry, Hybridization, and MO diagram of bromine trifluoride.
I hope you enjoyed reading my article and gained knowledge. If you still have any question floating in your mind, please let me know
Happy Reading!
