Bromine trifluoride is an inorganic compound with its chemical formula brF3. It is considered as an interhalogen compound. It is a straw-color liquid in its appearance having a pungent smell. Many students may have questions regarding whether bromine trifluoride is polar or not. In this article, I will answer this question and will cover its properties and applications
So, Is BrF3 Polar or Nonpolar? BrF3 (bromine trifluoride) is a polar molecule because of the presence of two lone pairs on bromine atom due to which the shape of the molecule is distorted or bent. And the distribution of charge on its atoms is non-uniform and the molecule turns out to polar in nature.
Bromine trifluoride is an interhalogen compound. At the standard conditions of temperature and pressure, it exists in a liquid state with a pungent smell.
It reacts vigorously with water and other organic compounds. It is a powerful fluorinating agent due to the presence of three fluorine atoms bonded.
It was first discovered in the year 1906 by a famous scientist Paul Lebeau. It was synthesized by reacting bromine with fluorine at a temperature of 20°C.
Below is the reaction for the reaction of the synthesis of bromine trifluoride.
Br2 (bromine) + 3F2(fluorine) ——> 2BrF3 (bromine trifluoride)
The molecular mass of this compound is 136.90 g/mol. It can be calculated as below
Mol mass of BrF3 = 1 * 79.9 (mol mass of Br) + 3 * 18.9 (Mol mass of F) = 136.90 g/mol.
If we talk about the chemical composition of bromine trifluoride, it consists of 1 bromine atom and 3 fluorine atoms.
The bromine is the central atom surrounded by the three fluorine atoms. The valence electrons of fluorine and bromine atoms are 7. Both atoms have 7 electrons in their outermost shell.
The valence electrons of BrF3 molecule is 28.
After three fluorine atoms get covalently bonded with bromine atom, the two lone pairs remain on the bromine atom.
The electronegativity of the fluorine atom is 3.98 and that of bromine atom is 2.96. The bromine atom being lesser electronegative comes at the central position.
The difference between the electronegativity of bromine and fluorine atoms generates the polarity across the Br-F bond with bromine with positive pole and fluorine as a negative pole.
It must be noted that the bromine atom has 2 lone pairs on it due to which the electronic repulsion between lone pairs and bonded pairs causes distortion in the shape ie; the bent shape is formed.
And therefore the charge distribution on its atoms is nonuniform ie; distributed unequally.
Why is BrF3 a Polar Molecule?
As discussed above the molecule of bromine trifluoride has three fluorine atoms surrounding one bromine atom.
The bromine atom has lone pairs on it due to which the electronic repulsion occurs.
As per the VSEPR theory, the repulsion between the lone pair and bond pairs generates the force on the Br-F bonds in the downward direction due to which the shape of the molecule is bent.
In addition to this, the electronegativity of bromine and fluorine atoms is different ie; fluorine is more electronegative than bromine.
The difference between the electronegativity of bromine and fluorine atoms ensures the polarity across the Br-F bond.
The dipole moment of the polar bond is always non zero. Similarly, all three Br-F also have some non zero value of its dipole.
And the net dipole of the molecule also turns out to be non zero having direction originated from the Br to the downward direction ie; fluorine side.
Due to the asymmetric shape and polar Br-F bonds, the entire molecule also becomes polar.
Polar versus Nonpolar Molecules
The molecules are held by the different types of interatomic forces. These forces can be ionic, covalent, hydrogen bonding, metallic bonding, etc.
Lets us check the difference between the polar and nonpolar molecules.
- Dipole moment: these molecules always have non zero dipole moment. As dipole of a molecule is the measure of its polarity.
- Electronegativity: the electronegativity of atoms forming a polar bond always differ with each other.
A higher electronegative atom becomes partially negative and another atom becomes partially positive. In this way, positive and negative poles are generated across the molecule.
- Geometrical shape: The shape of polar molecules is symmetric and that of nonpolar molecules are symmetric.
- Few examples of polar molecules are HBr, H2O. You can check out the reason for the polarity of HBr.
- Dipole moment: these molecules always have zero dipole moment.
- Electronegativity: the nonpolar bond formed between two atoms tends to have equal electronegativity.
- Geometrical shape: the shape of nonpolar molecules are symmetric.
- Some of the examples of nonpolar molecules are Hexane, NO2+. You can check out the reason for the non-polarity of NO2+.
Important points to determine the polarity of a molecule
Electronegativity: the electronegativity of an atom is its power to attract the bonded electron pair towards its side.
If there is a difference between the electronegativity of two atoms forming a covalent bond, the bond tends to be polar in nature.
This is because higher electronegative atom gains partial negative charge because the bonded electron pair is slightly nearer to it.
Similarly in BrF3 molecule, fluorine being higher electronegative gains a partial negative charge.
Dipole Moment: It is the measure of the polarity of a molecule. It is calculated as following
D = Q * R
D = dipole moment
Q = charges on atoms
R = distance between the centers of a negative and positive charge.
It is the product of the charges and the distance between the centers of both positive and negative charges.
Its SI unit is Debye and is denoted by D.
Geometrical shape: The shape of a molecule is an important point while determining the polarity of a molecule.
It is generally seen that a molecule that is symmetric in structure is nonpolar whereas asymmetric shape molecule is polar.
The shape of bromine trifluoride is also asymmetric due to which the distribution of charge is non-uniform.
Properties of BrF3
- It exists as a straw-colored liquid at room temperature.
- It is pungent in smell.
- The density of this substance is around 2.803 g/cm3.
- Its melting point is 8.77 °C or 47.79 °F and its boiling point is 125.72 °C or 258.30 °F.
- It is very easily soluble in sulphuric acid (H2SO4), and vigorously reacts with water.
Uses of BrF3
- It has great use in the formation of uranium hexafluoride (UF6) for the processing of nuclear fuel.
- It is also a powerful fluorinating agent therefore used in many chemical reactions as a fluorinating agent.
- This substance is also a strong ionizing inorganic solvent.
Bromine trifluoride (BrF3) molecule is bent in structure due to the presence of two lone pairs on bromine atom.
As per the VSEPR theory, its shape is distorted (bent shape). The electronegativity of bromine and fluorine has an appreciable difference due to which Br-F bond is polar.
So, due to distorted shape and polarity in Br-F bonds. The entire molecule has an unequal distribution of charge across it. As a result, Brf3 is a polar molecule.
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