BrCl4- Lewis Structure & Characteristics (11 Important Facts)

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BrCl4– is an interhalogen compound with molecular mass 221.716 g/mol. Let us discuss the structure and different characteristics of BrCl4– briefly.

BrCl4– possesses an octahedral geometry and square planar shape with two lone pairs and four bond pairs. Br, the central atom, is attached through four covalent bonds with the four chlorine atoms. It is a nonpolar molecule due to cancellation of bond dipole.

Let us explore the hybridization, bond angle, lone pairs, valence electrons, polarity with some relevant properties of BrCl4– in detail.

How to draw BrCl4– lewis structure?

Lewis structure is drawn to show the nonbonding electrons around each of the atom and give a clear idea about the shape of this molecule. Let us explain this.

Determining the valence electrons:

Br and Cl both are halogen molecule and both of them have seven electrons in their valence shell. But Br is negatively charged in BrCl4–, therefore, Br– has eight electrons in its 4s and 4p orbital.

Finding out the bonding electrons:

Br forms four covalent bonds with four chlorine atoms. Therefore, (4×2) = 8 electrons are involved in bonding.

Finding out the nonbonding electrons:

Br has four and chlorine has six electrons left as nonbonding electrons. These electrons are shown as electron dot in the below image.

brcl4- lewis structure
BrCl4– Lewis Structure

BrCl4– Lewis Structure Shape

Lewis structure shape tells about the three-dimensional arrangement of the atoms as well as the covalent bonds in a molecule. Let us talk about this.

The lewis structure shape of BrCl4– is square planar but the molecular geometry of this molecule is octahedral. The difference between this shape and geometry arises due to the presence of lone pair-lone pair, lone pair-bond pair and bond pair-bond pair repulsion.

Br has two lone pairs (four nonbonding electrons) which faces repulsion from each other as well as the Br-Cl bonding electron pairs. Therefore, from VSEPR theory, the shape as well as the geometry of BrCl4– is decided as square planar and octahedral respectively.

BrCl4– Lewis Structure Formal Charge

Formal charge is calculating to decide the most stable lewis structure as well as the individual charge of the constituent atoms. Let us discuss it.

The total formal charge of BrCl4– is -1, which can be calculated by using this formula= {Total number of valance electrons – number of electrons remain as nonbonded – (number of electrons involved in bond formation/2)}.

  • Formal charge of bromine atom = 7 – 4 – (8/2) = -1
  • Formal charge of the each of the chlorine atom = 7 – 6 – (2/2) = 0
  • Therefore BrCl4– is a negatively charged species.

BrCl4– Lewis Structure Angle

Lewis structure angle denotes the bond angle which contains two bonds and one atom (central atom). Let us give an over view on it.

The lewis structure angle of BrCl4– is 900 because the four Br-Cl bonds lie in the same plane as they occupy the four equatorial positions of an octahedral geometry. But the two lone pairs of bromine occupy the two axial position and the angle between them is 1800.

BrCl4– Lewis Structure Octet Rule

Octet rule is the rule of having eight electrons in the respective valence shell of any atom in a molecule like their nearest noble gas of periodic table. Let us comment on it.

BrCl4– does not obey octet rule as the constituent atoms of this molecule does not satisfy octet rule. Br already has seven electrons (4s2 4p5) in its outer most shell and it forms bond with four chlorine atoms. Therefore, it contains more than eight electrons in this molecule. Therefore, octet rule is not satisfied for Br atom.

But each of four chlorine atom satisfies octet rule as it has seven electrons and in bond formation with Br it achieves another electron through the Br-Cl bond formation. Therefore, it resembles with its nearest noble gas argon (3s2 3p6).

BrCl4– Lewis Structure Lone Pairs

Lone pairs are also called as nonbonding valence electrons which are not shared with other atoms in bond formation. Let us discuss it.

The lewis structure of BrCl4– contains 28 nonbonding electrons or 14 lone pairs which can be calculated by using this formula = (Total number of valance electron – number of bonded electrons). This can be obtained from the summation of the total lone pairs of bromine and chlorine.

  • Nonbonding electrons of bromine = 8 – 4 = 4 or 2 lone pairs.
  • Nonbonding electrons of each of the four chlorine atoms = 7 – 1 = 6
  • Therefore, total number of nonbonding electrons = 4 + (4×6) = 28 or 14 lone pairs.

BrCl4– Hybridization

Mixing of two atomic orbitals from two atoms to generate a new hybrid orbital (with different energies and shapes) is known as orbital hybridization. Let us clear it in detail.

The hybridization of BrCl4– is sp3d2. Br has four nonbonding electrons which occupy 4s and 4p orbitals. Rest of the four orbitals define the four Br-Cl covalent bond. Therefore, sp3d2 hybrid orbital is generated.

One s, three p and two d orbitals are involved in this hybridization of BrCl4–. From this hybridization, the molecular geometry as well as the shape of BrCl4– can be decided.

BrCl4– Valence Electrons

Any atom consists of electrons in different shells around its nucleus. Among them the electrons of its outer most shell is known as valence electrons. Let us explore this.

The total number of valence electrons in BrCl4– is 35. Br and Cl both are halogen atom and belongs to the p-block element. Both of then has seven electrons in their respective valence shell.

Br has electron configuration 4s2 4p5 and Cl has electron configuration 3s2 3p5. Therefore, BrCl4– has total valence electrons = 7 + (4×7) = 35.

Is BrCl4– polar or nonpolar?

Polarity or non-polarity can be decided by judging the relative arrangement of the covalent bonds as well as the polarity of the bonds. Let us find an overview on it.

BrCl4– is a nonpolar molecule. Though it has four polar Br-Cl covalent bonds but due to the arrangement of those bonds (bond angle between the bonds are 900) and octahedral geometry, it becomes a nonpolar molecule.

Why BrCl4– is a nonpolar molecule?

BrCl4– is a nonpolar molecule because all the bond moment of Br-Cl bonds are cancelled out by each other. One Br-Cl bond is oriented just opposite of another Br-Cl bond. Therefore, instead of having polar bonds, BrCl4– becomes a nonpolar molecule.

Is BrCl4– electrolyte?

Electrolyte are those which contains ions and are dissociated by electrolysis into two oppositely charged ions. Let us talk about this.

BrCl4– is not an electrolyte as it cannot be decomposed into ions in aqueous solution or any other solvent. it is a covalent compound. In most of the cases ionic compounds behave as electrolyte as they consist of two differently charged ions (cation and anion).

Is BrCl4– ionic or covalent?

Ionic or covalent character depends upon the bond formed between the atoms, whether it is formed by sharing or complete transferring of electron pairs. Let us discuss it.

BrCl4– is definitely a covalent compound. Br is central atom and it is connected through four covalent bonds with four chlorine atoms in BrCl4– and this covalency arises because the four Br-Cl bonds are formed due to the sharing of electron pairs.

Why BrCl4– is a covalent compound?

BrCl4– is a covalent compound because it forms four Br-Cl covalent bonds. Electrons are not completely transferred from one atom to another atom while these bonds are formed like any ionic compound. Besides that, there is no distinct positive and negative charge (cation and anion) in this compound.

Conclusion

BrCl4– is one of the most important interhalogen compound ICl3 ClF and many more. It is a covalent compound with zero dipole moment due to its octahedral geometry.

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