With a molecular weight of 186.26g/mol, BrCl3 is an interhalogen molecule.
Interhalogen molecules consist of two or more halogen atoms and no atoms from other groups. Several interhalogen chemicals are inherently unstable and predominantly covalent in character.
We draw the Lewis structure to better comprehend how atoms create bonds to form molecules. Before moving on to the lewis structure of BrCl3, please review the following terminology.
Valence Electrons
The valence electrons of an atom are the electrons in the outermost shell that participate in bond formation.
In order to complete their octate, it is necessary to donate or take electrons during bond formation. These valence electrons aid in the creation of bonds by being provided or received by other species.
To comprehend valence electrons, we must record the atom’s electrical state, from which we can readily determine the quantity of valence electrons.
Take chlorine with atomic number 17 as an example.
Configuration of Electronics = 1s22s22p63s23p5
We observe that the number of electrons in the outermost shell is seven (in 3s and 3p). Therefore, there are seven valence electrons in chlorine.
Octet Rule
Octet rule refers to the tendency for atoms to have eight electrons in their valence shell or achieve the configuration of the nearest noble gas. Typically, atoms with less than eight electrons create more stable compounds to complete their octet.
Hydrogen is an exception to the octet rule since it requires just two electrons to obtain the stable Helium gas state.
The Lewis Structure of BrCl3
The Lewis structure provides a simplified picture of the valence electrons present across a molecule’s atoms. It helps us distinguish between bound and unbonded electrons.
The Lewis structure of BrCl3 reveals that a total of 28 valence electrons are required to produce a single BrCl3 molecule (7 from bromine + 7(3) from 3chlorine atoms).
Let’s follow a sequence of steps that will facilitate our comprehension of the procedure for drawing the Lewis structure of BrCl3:
Step 1: Determine the total number of valence electrons present in BrCl3.
Both bromine and chlorine have 7 electrons in their valence shells, placing them in group 17 of the periodic table.
Consequently, the total amount of valence electrons in BrCl3 equals one valence electron in bromine plus three valence electrons in three chlorine atoms.
= 7 + 7(3) = 28
Step 2: Determine the electrons missing from each atom in order to achieve a stable electrical configuration. For one bromine atom and three chlorine atoms to form an octet, one electron is required for each.
Step 3 is to determine the overall number and kind of bonds formed between the concerned atoms.
For BrCl3, a single covalent bond is established between the bromine atom and each of the three chlorine atoms.
Step 4: Finally, we will determine the centre atom, which is typically the molecule’s sole atom.
In this instance, it is bromine.
We will now anticipate and sketch the Lewis structure of BrCl3 as shown below in step 5.
According to the Lewis structure of BrCl3, each chlorine atom possesses eight valence electrons, thereby completing its octet. Due to the enlarged octet, the bromine atom has a total of 10 valence electrons.
Observably, two lone pairs surround the bromine atom, whereas three lone pairs surround each chlorine atom.
This is how we predict and depict the Lewis structure, which enhances our understanding of molecular bonding.
BrCl3 Geometrical Structure
The Valence Shell Electron Pair Repulsion Theory (VSEPR) is utilised to predict the molecular geometry. This theory postulates that each molecule will achieve a shape that minimises the repulsion between each pair of electrons.
The number of electron pairs surrounding the core atom of a molecule can be calculated by drawing its Lewis structure.
Thus, the molecule’s geometry will be determined by the quantity of bonding and non-bonding electrons present on the central atom.
Three bonding pairs and two lone pairs surrounding the core atom of BrCl3 correspond to a steric number of five.
In this instance, it would recommend sp3d hybridization. Due to the presence of two lone pairs, BrCl3 will not have the ideal trigonal bipyramidal geometry, but will instead have a T-shaped geometry with an asymmetric charge distribution.
Due to the asymmetrical charge distribution caused by the presence of two lone pairs, the bond angle and bond length of BrCl3 are deviated from their ideal counterparts.
The nature of BrCl3’s structure is highly reactive.
BrCl3 Hybridization
Hybridization is the process of combining two or more atomic orbitals into new hybrid orbitals with the same energy, shape, and size. In valence bond theory, these newly created orbitals are known as hybrid orbitals and serve the goal of chemical bonding.
Upon observing the hybridization of the bromine atom in BrCl3, we observe that it is sp3d hybridised.
In sp3d hybridization, five identical hybrid degenerate orbitals are formed when one’s’ orbital joins with three ‘p’ orbitals and one ‘d’ orbital possessing nearly the same energy.
Examining the electrical structure of the valence shell of BrCl3 reveals the following: 4s23d104p5. To form a bond with three Chlorine atoms, the Bromine atom must have three unpaired electrons; hence, according to the Valence bond theory, the Bromine atom must undergo sp3d hybridization.
Upon hybridization, the three newly hybridised orbitals establish three bonds with three chlorine atoms, leaving two pairs of electrons in the two remaining orbitals to form lone pairs.
This explanation demonstrates the formation of 3 bonds in BrCl3 and the formation of 2lone pairs surrounding the bromine atom.
BrCl3 Polarization
Polarity is the separation of charges in a molecule due to the varying electronegativity of its constituent atoms. This results in a dipole moment with positive and negative ends.
Consider the T-shaped structure of BrCl3, which contains two pairs of lone electrons. Due to the presence of two lone pairs, the distribution of charge on the molecule will be asymmetric, and this distortion will result in the molecule’s polarity.
In addition, the Br-Cl bond’s difference in electronegativity is 0.2, resulting in a net dipole moment in the direction of the chlorine atom.
All of these factors demonstrate that BrCl3 is a polar molecule.
Conclusion
The Lewis structure of BrCl3 is comprised of three single covalent bonds between the bromine and chlorine atoms, as deduced from the preceding studies.
The hybridization of bromine in BrCl3 is created by the superposition of one’s’ orbital, three ‘p’ orbitals, and one ‘d’ orbital.
As an interhalogen compound, BrCl3 is an unstable and difficult-to-obtain substance. Due to the presence of two lone pairs, the bond angle of polar BrCl3 deviates from the ideal.
This concludes the article on BrCl3’s geometry, hybridization, polarity, and Lewis structure.
Read more: MO Diagram, C2H4 Lewis Structure, Molecular Geometry, and Hybridization
