Hybridization of BCl₃ ( Boron Trichloride)

Bookmark added to your notes.
View Notes

BCl₃ Hybridization 

SP² is the type of hybridization that appears in BCl₃. The boron in  BCl₃ is determined as a central atom that includes three bonded atoms but does not include a pair of electrons. The steric number of BCl₃ is said to be 3. Keep reading to know more about the Hybridization of BCl₃, BCl₃ Lewis Structure, BCl₃ Bond Angles, BCl₃ Molecular Geometry and Bond Angles, etc.

Name of Molecule 

Boron Trichloride

Molecular Formula


Type of Hybridization 


Bond Angle



Trigonal Planar

What is known as Hybridization?

The revolutionary concept of hybridization was introduced by Scientist Pauling.

It is defined as the intermixing of two atomic orbitals with similar energy levels to provide a degenerated new form of orbitals. This intermixing relies upon quantum mechanics. Only the atomic orbitals of similar energy levels can participate in hybridization and both partially and fully filled can also participate in this process, provided that they have similar energy.

The atomic orbitals of similar energy are mixed together during the process of hybridization such as the intermixing of 2 's' orbital or 2 'p' orbital or intermixing of 's' orbital with 'p' orbital or 's' orbital with  ‘d' orbital.

What Does the Hybridization of Boron Trichloride Mean?

To determine the way hybridization appears in Boron trichloride, we will take a central atom and examine a few attributes of it. We will examine the ground state of boron’s electron configuration. It will be 1s², 2s², 2p². Boron requires three unpaired electrons to form bonds with chlorine. In such a case, one electron from 2s is moved upwards to a level of 2p. Now, the electron configuration will be in the driven state and represented as 1s², 2s², 2px¹, 2py¹. 

[Image will be Uploaded Soon]

The BCL₃ hybridization now appears where one 2s and two 2p orbitals of boron will be actively participating in the process to form three half-filled sp² hybrid orbitals. Each sp² hybrid orbital will include paired electrons that will intersect with the unpaired electron in 3p orbital. Three chlorine atoms and three σ sp-p bonds are organized between boron half-filled sp² hybrid orbitals.

BCl₃ Lewis Structure

  • The BCl₃ lewis structure is similar to the BF₃( Boron Trifluoride), and BBr₃ ( Boron Tribromide) as F and Br falls in group 7 and includes 7 valence electrons.

  • Boron requires only 6 electrons instead of 8 to form an octron.

  • You can calculate the formal charges if you are not sure that you have an optimum BCl₃ Lewis Structure. You will examine that B in BCl₃ includes only 6 valence electrons.

  • There are a total of 24 valence electrons included in the BCl₃ Lewis Structure.

BCl₃ Bond Angles

The first step to determine the bond angles of BCl₃ is to form the Lewis structure.

For instance, BCl₃ is a trigonal planar and therefore it has a bond angle of 120⁰. However, when a molecule is polar, then it can't have bond angles exactly of 120⁰ even if it is trigonal planar in shape.

Another example we can take is CHICO, in such a case a bond angle cannot deviate too far away from 120⁰ as it does not include lone pair electrons. Molecules that include a lone pair on a central electron will cause repulsion and that is the basic reason behind it.

The BCl₃ bond angle will be less than 120⁰ if the molecule retains two bonding groups and only one pair of electrons and causes a bent molecular shape. Due to lone pair electrons, the molecules that have similar domain geometry can have distinct molecular geometries.

BCl₃ Molecular Geometry and Bond Angles

[Image will be Uploaded Soon]

If we examine the structure, we can find that BCl₃ molecular geometry is trigonal planar and the BCl₃ bond angle is 120⁰. The central atom molecule is nonplanar and has a symmetric charge around it. 

Important Points to Note

  • Boron forms 3 σsp-p bonds with 3 chlorine atoms.

  • An unpaired electron will be included in each sp² hybrid orbital.

  • One 2s and two 2p orbitals of boron will form 3sp² orbital electrons during hybridization.

FAQ (Frequently Asked Questions)

1. What are the Uses of Boron Trichloride?

Answer: The uses of Boron Trichloride are as follows.

  • The basic material used in the production of elemental boron is Boron Trichloride. 

  • Boron Trichloride is also used in the refining of magnesium, zinc, aluminum to remove oxides, carbides, and nitrides from molten metal.

  • It is used in plasma etching in the manufacturing process of semiconductors.

  • BCl₃ acts as a reagent in the synthesis of organic compounds.

  • A uniform and lasting adhesive carbon film can be placed over a ceramic base using BCl₃ in the manufacturing of electrical resistors.

  • BCl₃ is used in the manufacturing of electrical resistors.

  • BCl₃ can be used as a soldering flux for alloys of aluminum, iron, tungsten.

Aluminum casting can be improved by treatment with Boron Trichloride.

2. Explain the Meaning of Boron Trichloride.

Answer: Boron trichloride is a colourless gas that is an important reagent in organic syntheses but is also hazardously effective. Boron Trichloride is produced in industries by direct chlorination of boron oxide and carbon at 500°C. The combination is comparable to the Kroll process for the conversion of titanium oxide to titanium tetrachloride. In the laboratory, BCl₃ is formed by reacting to BF₃ with AlCl₃. Boron trichloride does not arrange dimers, although there is some dimerization at very low temperatures (20k). NMR studies of mixtures of boron trihalides show the indication of mixed halides, which may demonstrate a four center intermediate ( that is, a dimer). The non-existence of dimerization diverges with other trihalides of group 13 which includes 4 or 6 coordinated metal centers.