Boron trichloride (BCl3) is an inorganic compound that appears as a colorless gas and has a pungent odor. Its gas is very irritative to the mucous membranes, eyes and corrosive to the metals.
BCl3 is a corrosive agent and will form hydrogen chloride when exposed to moisture or alcohol.
The net dipole moment of PCl3 is greater than BCl3 because the bond and lone pair don’t cancel each other.
The BCl3 easily accepts a pair of an electron from the water, when it reacts with water and produces hydrogen chloride and boric acid which reaction is given below.
BCl3 + 3H2O → H3BO3 + 3HCl
Are you wondering is BCl3 polar or nonpolar? This article will help you clarify all your confusion about BCl3 polarity and its molecular geometry.
If you want to know about BCl3 further, read the whole article and try to understand BCl3 properties, uses, and Lewis structure.
The formula of boron trichloride is BCl3.
Is BCl3 Polar or Nonpolar
Boron trichloride (BCl3) is a nonpolar molecule because chlorine’s halides are symmetrically located around the central boron atom, which cancels out polar covalent bonds.
Boron trichloride (BCl3) is a nonpolar molecule because the three bonds’ polarities are precisely canceled out of each other due to symmetry. Therefore the molecules are polar, which resulting BCl3 is a nonpolar molecule, but the bonds are polar due to the electronegativity difference.
BCl3 is nonpolar because, in BCl3, we have three chlorine atoms, which have a negative charge, and the boron in the center has an equal positive charge.
The boron balance out three chlorides because boron has 3 valence electrons. The boron is okay if they did not fill the octet, but it can still produce a nonpolar molecule, which resulting BCl3 is nonpolar.
BCl3 is nonpolar due to its symmetrical structure, and due to the difference of electronegativity, the B-Cl bond is polar and lies at 120 degrees to each other. The electronegativity of boron is 2.04, and chlorine is 3.16. As a result, each B-Cl bond’s dipole moments cancel each other out. This is why BCl3 is considered a nonpolar molecule.
Simple is that BCl3 is a nonpolar molecule. If you want to know the reasons in detail, read the above four explanations.
BCl3 Molecular Geometry
The molecular geometry of BCl3 is trigonal pyramidal. The boron is located in the center, which has three valence electrons and balances out the three chlorine. This is because the molecular arrangement of the chlorine atom is part of a complete triangular shape.
The boron does not complete its octet full, but it still has the ability to make a molecule nonpolar.
In BCl3, the charge distribution is symmetric around the central atom.
It takes AX3 notation according to as per VSEPR notation. The bond between B-Cl is a single bond and has no lone pair throughout B. There is a total of 6 electrons around B.
Simple is that the molecular geometry of BCl3 is trigonal pyramidal.
BCl3 Lewis Structure
To draw the BCl3 Lewis structure, follow the below instructions.
- First of all, find out the total number of valence electrons in the NH3 using the periodic table.
- In BCl3, boron (B) is in group 3 in the periodic table and has three valence electrons. Chlorine is in group 7 and has seven valence electrons, but we have three chlorine. Therefore, we will multiply 7(3)=21
- To find the total number of valence electrons in the BCl3, we will add boron (B) and chlorine (Cl) valence electrons, which become 3+21= 24.
- Now we know that we have a total of 24 valence electrons in the BCl3.
- Put the boron (B) in the center and add chlorine around it.
- To form a chemical bond between each atom, put the electrons between chlorine and boron.
- Used all valence electrons to complete the octet.
- At last, only the boron does not have an octet, but the boron does not necessarily have eight electrons.
- Now remove the two valence electrons from the chlorine atom’s left or right side to make a double bond that gives the eight electrons for bromine and chlorine atom.
- You have two structures right now. One has a double bond, and the other one six electrons in the boron, so here the problem is which one is the correct structure in both of them?
- To find out the correct one, you can use the idea of a formal charge.
You may not understand this formula properly theoretically; therefore, I will recommend watching this video that will guide you to select the correct structure using the equation.
Hybridization Of BCl3
The hybridization of BCl3 is sp2.
Here is the simple formula for calculating hybridization.
Find out the number of valence electrons over the central atom. + Atom around the central atom and then divide it by 2.
The number of valence electrons in the boron atom is 3, and the number of the monovalent atom is three ( which are three chlorine).
So add it and divided by 2, which becomes 3+3= 6/2= 3
The result is 3, and 3 stands for sp2. This is how you can calculate hybridization.
Simple is that the hybridization of BCl3 is sp2.
Is BCl3 Ionic Or Covalent
The BCl3 is a covalent bond, but the molecules are polar, so due to not individual bond, it causes positive and negative charge, which allows BCl3 for a polar bond.
The bonds are polar because of the boron and chlorine electronegativity difference.
Nitrogen (NH3) has a unique pair of unused electrons and is rich in electrons, while the boron atom in BCl3 lacks electrons. The interaction between the N and B atoms will cause the pair of molecules’ energy to decrease. Thereby the molecules have a stabilizing effect on the complex.
BCl3 has an covalent bond.
BCl3 Dipole Moment
The dipole moment of BCl3 is Zero because of the electronegativity difference between chlorine and boron atom. The geometry of the BCl3 is also nonplanar. The chlorine is more electronegative than the boron.
The B-Cl forms a polar bond and have a planar molecular compound.
As a result, each B-Cl bond’s dipole moments cancel each other out.
The dipole moment of BCl3 bonds is zero.
The same is the case of BCl3 and BF3. Both have zero dipole moment, which cancels out each other dipole moment.
Simple is that the BCl3 has zero dipole moment.
BCl3 Bond Angle
The bond angle of BCl3 is 120 degrees. You can determine the bond angle while drawing its lewis structure.
As I have discussed that BCl3 molecular geometry is trigonal planar. Therefore, the bond angle of BCl3 is 120 degrees. If you are still confused to know about the bond angle, remember this simple tip that the molecule with linear and trigonal planar shape mostly has a bond angle of 120°.
BCl3 has bond angle of 120°.
Properties Of Boron trichloride (BCl3)
- The molar mass of the BCl3 is 117.17 g/mol.
- It exists as colorless gas at room temperature and fumes in the air.
- Its boiling point is 12.6 °C or 54.7 °F, and melting point is −107.3 °C or −161.1 °F.
- It is soluble in ethanol and ccl4.
- Its magnetic susceptibility is -59.9·10−6 cm3/mol.
Above are the properties of BCl3.
Uses Of Boron trichloride (BCl3)
- The Bcl3 is the starting material for the production of elemental boron.
- BCl3 is used for the refining of magnesium and zinc-aluminum.
- It is also used plasma etching, which is used to fabricate integrated circuits.
- BCl3 is used as a reagent in the synthesis of organic compounds.
- It has been used as a flux for aluminum, iron, zinc, tungsten, and Monel alloys.
Above are the uses of BCl3.
That was all about is BCl3 polar or nonpolar. I hope it’s now clear to you that Boron trichloride (BCl3) is a polar molecule because of its symmetrical structure and electronegativity difference.
The BCl3 has trigonal pyramidal molecular geometry, and the boron is located in the center.
If you are confused about drawing the Lewis structure of BCl3, watch the above video to clarify all your confusion.
It has an sp2 hybridization, and the bond making in BCl3 is a covalent bond, but the molecules are polar.
Its dipole moment is zero and has 120 degrees of bond angle.
Do you think we have missed something about the BCl3 topic? Let us know in the comments section below we will add them.