21 Facts On BCl3 Lewis Structure & Characteristics: Why & How?


BCl3 lewis structure is an industrial molecule with immense benefits. Its complete discussion is illustrated in this article.

BCl3 lewis structure or Boron trichloride is formed by sharing of electrons between 1 boron and surrounding 3 chlorine atoms by a single covalent bond. Here chlorine achieves octet stability and boron is octet deficient or electron deficient forming sextet.

BCl3 lewis structure is an inorganic compound that is a colorless gas and used in organic synthesis as catalysts and reagents. It is a starting material and is used to extract elemental boron. Apart from that BCl3 lewis structure plays many roles in the metallurgical industry as a refining agent and soldering flux. Let us discuss these properties in detail.

How to draw the BCl3 lewis structure?

Drawing the BCl3 lewis structure provides us insight into the compound from every aspect. Let us describe these in a stepwise manner.

Step1: Calculating the total number of valence electrons in the BCl3 lewis structure

Being aware of the electrons participating in the bonding is important step in the BCl3 lewis structure for which we need to calculate total number of valence electrons by adding all of them. B has 3 and Cl has 7 valence electrons. So the calculation will be 3 + 7(3) = 24 valence electrons.

Step2: Selection of the central atom

Choosing the central atom is the next important step in BCl3 lewis structure for understanding the framework. The central atom in the BCl3 lewis structure is Boron which is the least electronegative atom. The reason behind choosing it is the electronic symmetry and distribution it provides.

Step3: Completion of the octet criteria

Making sure the octet criteria are fulfilled is the next step after establishing the framework of the molecule. Octet stability criteria of all Cl atoms are fulfilled by sharing through single covalent bonding. B on the other hand forms a sextet and is an electron-deficient species.

Step4:  Checking the formal charge in the BCl3 lewis structure

Formal charge calculation is the end step in the BCl3 lewis structure. The formal charge of Boron and Chlorine in the BCl3 lewis structure is 0. A less formal charge without the violation of the structural bonding is an indication of a stable molecule and confirms the existence of the molecule. 

BCl3 lewis structure
BCl3 lewis structure

BCl3 lewis structure resonance

Resonance or mesomerism is a phenomenon observed in polyatomic molecules where different structures are formed of a single molecule. Let us discuss resonance of this structure.

BCl3 lewis structure does not exhibit resonance. This implies that only a single structure of the BCl3 lewis structure can explain all the properties associated with it and hence there are no resonating or canonical structures attached to it.

The reason behind the no resonance phenomenon in BCl3 lewis structure is the absence of conjugated unsaturation and the delocalization of pi electrons. Here there are no pi electrons so the alternation between bonds is not possible. Hence BCl3 lewis structure has no resonance.

BCl3 lewis structure molecular geometry

The concept of molecular geometry is based on the arrangements of atoms in the most stable way in the molecule. Let us find out the molecular geometry of the BCl3 lewis structure.

The molecular geometry of the BCl3 lewis structure is trigonal planar. B is the central atom surrounded by 3 Cl atoms and has no lone pairs. Because of the minimum repulsions, the electron density is uniform around 3 regions which affords trigonal planar as the best geometry.

Another way to find out the molecular geometry is by VSEPR chart and the AXN method. Here A is the central atom boron and X is chlorine. As there are no lone pairs so N will be 0. This gives AX3N0 or AX3 geometry.

BCl3 lewis structure 3D representation

BCl3 lewis structure formal charge

Formal charge calculation is one of the important steps when it comes to assessing the stability of the structure. Let us know its formula and calculate for the BCl3 lewis structure.

Formal Charge of an atom = Valence electron of an atom – Nonbonding electrons of an atom – Bonding electrons around an atom/2.

Let us calculate the formal charge of boron and chlorine in the BCl3 lewis structure.

  • Formal Charge of chlorine atom in BCl3 lewis structure = 7 – 6 – 2/2 = 0
  • Formal Charge of boron atom in BCl3 lewis structure = 3 – 0 – 6/2 = 0
  • Hence BCl3 lewis structure is stable and reliable.

BCl3 lewis structure angle

The bond angle is decided by many factors associated with the frame of the molecule. Let us figure out the bond angle for the BCl3 lewis structure.

The bond angle of the BCl3 lewis structure is 120 degrees. The molecular geometry of the BCl3 lewis structure is trigonal planar. So according to that convention, the angle of each B-Cl will be 120 degrees.

There is the absence of lone pair of electrons in the BCl3 lewis structure which implies that the structure is uniform from all the sides and planes. So the possibility of angle distortion is not there in the BCl3 lewis structure.

BCl3 lewis structure bond angle

BCl3 lewis structure octet rule

Octet rule fulfillment is a stability criterion that can be achieved by sharing, gaining, or losing electrons. Let us figure out the same in the BCl3 lewis structure.

Chlorine atoms fulfill the octet criteria but boron is an exception to it.  Chlorine has 7 valence electrons and needs 1 to complete octet which is by sharing through a single covalent bond. Boron on the other hand is electron deficient.

Boron is an anomaly to the octet rule where instead of forming an octet it forms a sextet due to its electron-deficient nature. So boron in BCl3 lewis structure, unlike chlorine, shares 3 electrons and has a total of six electrons after sharing.

Is BCl3 lewis structure an expanded octet?

Expanded octet-like electron deficiency is an anomaly to the octet rule. Let us check out whether the BCl3 lewis structure follows the same or not.

BCl3 lewis structure does not follow the concept of an expanded octet. Instead, it is an electron-deficient compound where the central boron atom forms the sextet by sharing through single covalent bonding. 

Expanded octet or super octet or hypervalent is shown by compounds where the central atom has a large size and due to that it can accommodate more than 8 electrons. Boron in the BCl3 lewis structure is of small size and hence it does not follow the concept. 

BCl3 lewis structure lone pairs

Lone pairs are the extra valence electrons that have no role in bonding. Let us find out the lone pair in the BCl3 lewis structure. 

There are no lone pair of electrons in the BCl3 lewis structure. It is important to note that the lone pair of central atoms are significant. After sharing there is no extra electron left on the boron.

There are 3 valence electrons in a boron atom and all 3 of them participate in bonding with chlorine through a single covalent bond. This leads to no lone pairs. Apart from this lone pairs on central and not on terminal atoms are significant because they are responsible for the changes and distortions.

BCl3 lewis structure valence electrons

Valence electrons are crucial in chemical bonding because they are in the outermost region. Let us figure out the valence electrons in the BCl3 lewis structure.

In the BCl3 lewis structure boron has 3 valence electrons and chlorine has 7 valence electrons. The total no. of valence electrons in a molecule can be calculated by the addition of valence electrons in the individual atoms.

Let us calculate the no. of valence electrons in the BCl3 lewis structure.

  • Valence electrons in boron = 3
  • Valence electrons in chlorine = 7
  • Total number of valence electrons in BCl3 lewis structure = 3 + 7(3) = 24

BCl3 lewis structure hybridization

Hybridization is the intermixing of the orbitals with different energies to form new hybrid orbitals. Let us find out the hybridization of the BCl3 lewis structure.

The hybridization of the BCl3 lewis structure is sp2 as the steric number of the central boron atom is 3.  Steric number = Number of bonded atoms with central atom + Lone pair around the central atom.

Let us calculate the steric number using the above-given formula.

  • Number of bonded atoms with central atom = 3
  • Number of lone pairs around the central atom = 0
  • Steric number = 3 + 0 = 3
  • So according to the notion, the hybridization of the BCl3 lewis structure is sp2. 

Is BCl3 lewis structure ionic or covalent?

The ionic or covalent character of any lewis structure is based on the arrangement of electrons in that structure. Let us see the same in the BCl3 lewis structure.

BCl3 lewis structure is a covalent compound. There is sharing of electrons between boron and chlorine which leads to the formation of 3 B-Cl single covalent bonds.

Why is BCl3 lewis structure ionic or covalent?

There are many deciding factors when it comes to finding the bond character. Let us check the reason behind it in the BCl3 lewis structure.

The bond is covalent in BCl3 lewis structure because there is sharing of electrons instead of direct transference. So no positive and negative charges are denoted to the individual atoms and hence no ion formation is observed.

Apart from this BCl3 lewis structure involves one boron atom and three chlorine atoms. Both of these atoms are nonmetals which again is a big factor behind the sharing of electrons and the covalency of the molecule.

Is BCl3 lewis structure polar or nonpolar?

The polarity of the compound is based on its interaction between the individual atoms. Let us check whether the BCl3 lewis structure is polar or nonpolar.

BCl3 lewis structure is a nonpolar compound. It is very evident from the structure that its symmetrical bond angle cancels out the dipole moment and hence is nonpolar.

Why is BCl3 lewis structure polar or nonpolar?

There are certain reasons behind the nonpolar nature of the BCl3 lewis structure. Let us explain it.

BCl3 lewis structure is polar as atoms B and Cl have sizable differences in their electronegativities which means that boron has a partial positive charge and chlorine has a partial negative charge. But still, they are nonpolar due to the cancellation of the dipole moment.

BCl3 lewis structure is a symmetrical molecule. Despite the greater electronegativity difference, the B-Cl dipole gets canceled out due to the geometry which makes the whole molecule nonpolar.

Is BCl3 lewis structure a lewis acid or base?

The lewis acid-base concept is based on the acceptance and donation of electrons. Let us figure out whether the BCl3 lewis structure is a lewis acid or base.

BCl3 lewis structure is a lewis acid. The structural or electron dot symbol representation can explain the reason behind this consideration.  The electrons around the central atom boron decide that the whole BCl3 lewis structure is a lewis acid.

Why is BCl3 lewis structure a lewis acid?

The nature of boron in BCl3 lewis structure is the main factor behind the fact that it is a lewis acid. Let us find out how the acid-base theory works in the case of the BCl3 lewis structure.

BCl3 lewis structure is a lewis acid because boron is an electron-deficient species forming only a sextet instead of an octet. So whenever it reacts with any base then it can accept electrons which are the basic characteristics of lewis acids.

A reaction between the BCl3 lewis structure and NH3 shows that despite the absence of a hydrogen atom in the BCl3 lewis structure it can accept the lone pair from NH3 making it a lewis acid and NH3 as a lewis base.

Is BCl3 lewis structure a bronsted base?

Bronsted lowry concept can be used to explain the characteristics of BCL3 lewis structure. Let us figure out whether the BCl3 lewis structure is a bronsted base or not.

BCl3 lewis structure is not a bronsted base. This is because it has a complete structure and cannot accept hydrogen atoms which is a basic requirement to be a bronsted base.

Why is the BCl3 lewis structure not a bronsted base?

BCl3 lewis structure as a whole does not follow the bronsted lowry concept. Let us figure out the reason behind it.

BCl3 lewis structure si not a bronsted base as it is an electron-deficient species and in the reaction, it can accept electrons. But to be a bronsted base it should accept hydrogen ions which is not a possibility for it.

The bronsted acid-base concept is based on a hydrogen count before and after the reaction. A decrease in the hydrogen ions implies bronsted acid and an increase implies boosted base.

Is BCl3 lewis structure a nucleophile?

The concept of nucleophilicity is the core of organic chemistry. Let us discuss it in the context of the BCl3 lewis structure.

BCl3 lewis structure is not a nucleophile. Nucleophiles are nucleus-loving species but BCl3 lewis structure is not nucleus deficient, instead it electron-deficient species. Hence it is not a nucleophile in organic reactions.

Why is BCl3 lewis structure not a nucleophile?

The electron distribution in the BCl3 lewis structure could explain the reason behind its non-nucleophilicity. Let us lookout for the same.

BCl3 lewis structure is not considered a nucleophile as it is an electron-deficient species as the central boron atom has only six electrons. So it can accept a pair of electrons which is not a characteristic of a nucleophile.

Instead, the BCl3 lewis structure is an electrophile that accepts electrons from the nucleophile. Also, the boron has empty 2pz orbitals perpendicular to the plane which makes the acceptance of electrons easy.

Is BCl3 lewis structure soluble in water?

Solubility criteria of a molecule are based on whether it is organic or inorganic. Let us discuss in detail about BCl3 lewis structure.

BCl3 lewis structure is soluble in water. It is highly reactive in water and even undergoes hydrolysis reaction.

Why is BCl3 lewis structure soluble in water?

Let us lookout the reason behind the easy solubility of BCl3 lewis structure in water

BCl3 lewis structure is soluble in water because it is an inorganic compound and has a significant polar character. Apart from that, it is also soluble in an organic solvent which is a unique character of the molecule.

Is BCl3 lewis structure liquid?

The nature of any molecule in the context of its states of matter depends on the forces which hold the atoms in that molecule. Let us discuss the state of matter in the BCl3 lewis structure.

BCl3 lewis structure is a liquid or exists in the liquified form in nature. It is a colorless liquid and has a strong and pungent odor associated with it. It is a fuming liquid but it does not burn in the air. In humid conditions, it exists in the form of smoke.

Why is BCl3 lewis structure liquid?

The composition of every structure is unique to its properties and characteristics. Let us discuss the liquid nature of the BCl3 lewis structure.

BCl3 lewis structure is a liquid because its atoms have less intermolecular spaces and more intermolecular forces. It is a strong fuming liquid that is corrosive but under strong pressure, it can form gas.

The BCl3 lewis structure gas is much more strong when in its gaseous form and can affect skin and eyes. But its natural liquid is not very strong or something to be cautious about.

Is BCl3 lewis structure more stable than TlCl3 lewis structure?

The stability comparison of BCl3 lewis structure with TlCl3  involves the oxidation state in which they exist. Let us discuss it in detail.

Between BCl3 lewis structure and TlCl3 BCl3 lewis structure is more stable. Boron has a +3 oxidation state and thallium shows a +1 and +3 oxidation state. Keeping inert pair considerations in mind the BCl3 lewis structure comes out to be more stable.

Why is the BCl3 lewis structure more stable than the TlCl3 lewis structure?

The detailed answer to the stability difference between BCl3 lewis structure and TlCl3 can be found using periodic properties. Let us dig deep into the same.

BCl3 lewis structure is more stable than TlCl3 because both belong to group 13 of the periodic table. Here both the compounds have a +3 oxidation state. But the oxidation state of B is more stable than Tl down the group.

In group 13 +1 oxidation state is more stable as compared to the +3 oxidation state going down the group from top to bottom according to the convention. The +3 oxidation state though observed in both compounds is highly oxidizing in TlCl3 and reverts to the +1 state.

Is BCl3 lewis structure more acidic than AlCl3?

The acidity comparison of two structures involves the orbitals and their pH configuration. Let us figure out whether the BCl3 lewis structure is more acidic than AlCL3 or not.

BCl3 lewis structure is more acidic than AlCl3 because of the pH difference where AlCl3 has pH 6.5 and BCl3 lewis structure pH is 5.5. So the reaction with base and further salt formation is easier in the BCl3 lewis structure.

Why is BCl3 lewis structure more acidic than AlCl3?

Apart from the pH factors, there are molecular factors associated with acidity. Let us throw some light on the reason behind this.

The reason why BCl3 lewis structure is more acidic than AlCl3 as the reaction with base 2p orbital of boron in BCl3 lewis structure shows overlap with base. This overlap is much stronger as compared to the 3p orbital overlap of aluminium.

Apart from this boron has much more electronegativity than aluminium. Hence it easily accepts the electron. Aluminium, on the other hand, forms a dimer and can form a dimer that inhibits acidic behavior. 

Does the BCl3 lewis structure have a high melting point?

Melting point is one of the physical characteristics of any structure. Let us discuss the melting point of the BCl3 lewis structure.

BCl3 lewis structure does not have a high melting point. Its melting point is rather very low is -107.3 degrees celsius. Even its boiling point is low as compared to my other lewis structures.

Why does the BCl3 lewis structure not have a high melting point?

The physical characteristics of any structure are directly related to its bonding. Let us check the same behind the melting point of the BCl3 lewis structure.

BCl3 lewis structure has a low melting point because it is a covalent compound. The covalency or sharing of electrons has led to a negative melting point where the application of sudden pressure or temperature can change the state of matter.

A high melting point is observed in ionic compounds with electrovalent bonding where the attractions are so strong that it is very tough to break the bond. The situation is the opposite in covalent compounds including the BCl3 lewis structure.

Is BCl3 lewis structure symmetrical?

The symmetry of a molecule can be judged from its molecular geometry. Let us check whether the BCl3 lewis structure is symmetrical or unsymmetrical.

BCl3 lewis structure is a symmetrical molecule with trigonal planar geometry. This implies that all the three B-Cl bonds are symmetrical when cut through the half from the axis plane.

Why is the BCl3 lewis structure symmetrical?

Symmetrical nature is usually judged in 3D planes and by keeping the geometry in consideration. Let us look out for the same in the BCl3 lewis structure.

BCl3 lewis structure is symmetrical with axis of symmetry is C3v. This means that the axis symmetry passes through the center of the molecule and the left-hand side is equal to the right-hand side proving the symmetry of the molecule.

Another easy method to be sure about the symmetry is to focus on the shape and the no. of lone pairs involved. In the BCl3 lewis structure, there are no lone pair of electrons and the geometry is trigonal planar. Hence chances of distortion due to repulsion are minimized which maintains its symmetrical position.

Conclusion

In nutshell, BCl3 lewis structure is an inorganic compound with significance in organic chemistry as a reagent and catalyst where it shows characteristics of both the classes. It is an electron-deficient compound with a covalent character and exhibits electrophilicity.

Mansi Sharma

Hello, I am Mansi Sharma, I have completed my master's in Chemistry. I personally believe that learning is more enthusiastic when learnt with creativity. I am a Subject Matter Expert in Chemistry. Let's connect through LinkedIn: https://www.linkedin.com/in/mansi-sharma22

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