What is the polarity of BF3?

An inorganic chemical compound known as Boron Trifluoride, BF3 is a colourless gas with an unpleasant odour.

Fluorine’s high electronegativity makes it difficult for students to determine whether or not BF3 (Boron Trifluoride) is positively or negatively polar.

Is BF3 polar or non-polar, then? For this reason, Boron Trifluoride (BF3) is Non-Polar. The three BF bonds’ dipole moments are cancelled out by the compound’s trigonal planar shape, resulting in a Dipole Moment of 0. (Zero).

Let’s take a closer look at this. In order to get an answer, we’ll look at the major BF3 polarity considerations.

The table of contents for this section can be found here.

Its molecular structure can be summarised as follows: (Boron Trifluoride)

B (Boron, number 5) and F (Fluorine, number 2) are the only atoms of B that make up the BF3 molecule (Fluorine, atomic no: 9). The Lewis structure of BF3 can be depicted as shown in the image, because the valency of B (Boron) and F (Fluorine) are both 3.

Its chemical structure is BF3

The molecular structure is balanced and symmetric because each F (Fluorine) atom has three lone pairs of electrons.

Each F-B-F bond angle in the BF3 (Boron Trifluoride) molecule is 120 degrees, according to the VSEPR (Valence Shell Electron Pair Repulsion) Theory, making the molecule very symmetric as shown:

Aspects of BF3’s Electronegativity and Bond Polarity (Boron Trifluoride)

As depicted in the Lewis diagram above, BF3 (Boron Trifluoride) has three B-F bonds.

As a result of the Pauling scale, the electronegativity of B is 2.04 and the electronegativity of F (Fluorine) is 3.98 (maximum). This means that F (Fluorine) will pull the shared electrons towards itself and thus acquire a partial negative charge (-) and B (Boron) will have a partial positive charge (+).

For a bond to be polar, we must identify the difference in electronegativity values between the two atoms that share a bond.

The electronegativity difference between B and F is bigger than 0.5 because it is equal to 1.94 (3.98 – 2.04 = 1.94)

Since the BF3 molecule has three B-F bonds, each one is polar. Because the electrons are not shared equally between the two atoms (B and F), the electrons tend to gravitate toward F. (Fluorine).

Bond polarity, on the other hand, is distinct from molecular polarity. Overall molecular polarity is not usually the product of bond polarity.

Brayton’s Force 3 Dipole Moment (Boron Trifluoride)

Boron Trifluoride (BF3) has a bond dipole moment because of the polarity of the three B-F bonds.

Dipole Moment of BF3

However, as previously noted, BF3’s highly symmetrical structure and geometry allow the bond dipole moments to be cancelled, resulting in a Molecular Dipole Moment of 0. (Zero).

Non-Polarity of the chemical BF3, Boron Trifluoride.

As predicted by the Valence Shell Electron Pair Repulsion Theory, the Trigonal Planar geometry of BF3 (Boron Trifluoride) is the reason for its Non-Polarity, which other molecules, like H2O, do not have.

If we want to figure out whether or not a specific molecule is polar or non-polar, we also need to know what causes polarity. These aspects are described in depth in the following paragraphs.

Structure and Geometry of Molecules

When it comes to molecules, structure and geometry play an important role in determining the molecular polarity. The overall molecule’s dipole moment is either 0 (Zero) or not depending on the bond angle between the two molecules.

In order to determine the bond angle, we use the VSEPR (Valence Shell Electron Pair Repulsion) Theory.

It is possible to see all of the molecules’ lone electron pairs in their Lewis structures.

The molecule gets polarity when the unbalanced, or unsymmetrical, electron pairs remain (like in NH3 where the Nitrogen atom has the lone pair).

Non-Polar molecules are those with a high degree of symmetry (like BF3).

Check out the article on BF3 Lewis Structure, Molecular Geometry, and Hybridization for additional information.


The symbol for electronegativity is (Greek letter Chi). An atom’s ability or force to pull the shared electrons of a link toward itself might be described as uneven sharing because of this property.

The more electronegativity an atom possesses, the more likely it is to draw electron pairs from a link toward itself.

To begin with, the atomic number and second, the distance between the positively charged nucleus and an atom’s valence electrons, are used to make this determination.

Linus Pauling has published a periodic table of the electronegativity of elements. What element’s electronegativity is the highest? Fluorine’s, at 3.98.

Polarity of a bond

To determine if a combination is polar or non-polar, we must first define what we mean by “Polarity.”.

To produce a compound, atoms of various elements must make a bond with each other. In this relationship, electrons are shared between the elements, but this sharing is never equal.

Both elements gain partial negative and partial positive charges as a result of their differing levels of electronegativity, which are determined by the electronegativity of the two elements..

As a result, charge separation and bond polarity emerge within the bond. The electronegativity difference between the two atoms must be larger than or equal to 0.5 for a bond to be considered polar.

In contrast, bond polarity alone is not enough to produce a molecular structure polar.

Momentum of Dipole

In order for a bond to create a dipole moment, it must acquire polarity, which is the separation of charge, through the bond. The polarity of an atom-to-atom bond can be measured using this term.

According to this illustration, dipole moments are portrayed using a somewhat different type of symbol, which has an arrowhead that points toward the negative centre.

  • ———————>

In molecules with symmetrical geometry, like BF3, the dipole moments of the two opposing bond dipoles cancel each other out, making the dipole moment a vector quantity with both magnitude and direction.

‘D’ is the abbreviation for Debye Unit. C is the unit of charge, and the metre is the unit of length; so, 1 D = 3.33564 * 10-30 C/cm. The molecule’s shape and structure must be known in order to compute the dipole moment. The following formula can be used to determine a bond’s dipole moment mathematically:

Diamagnetic Moment () = Charge (Q) * Separation Distance (r)

When the dipole moments of all the bonds cancel and the resulting dipole moment is equal to 0, a molecule can be non-polar (like BF3) despite having all its bonds be polar (Zero).

It’s now easy to see how the BF3 molecule is non-polar, even though it contains fluorine, a strongly electronegative element, in its structure.

What BF3 is made of

Hydrofluoric acid, which forms when Boron Trifluoride dissolves in water, is extremely corrosive because of its high solubility in cold water.

Metals such as stainless steel can be corroded by it. It has a solubility of 106 percent in cold water.

It’s possible for containers of BF3 to explode or rocket if they’re exposed to heat or fire for a long period of time.

Stable in dry air despite the fact that it is colourless but creates dense white vapours in damp air due to the presence of H2O molecules.

Also harmful when heated for decomposition is Hydrogen Fluoride, which emits toxic and corrosive vapours when heated.

Unsaturated chemicals can also be polymerized using BF3.

BF3’s applications (Boron Trifluoride)

There are numerous applications for BF3 (Boron Trifluoride) in a variety of sectors.

A wide range of applications include adhesives and sealant chemicals, adsorption and adsorption agents, fuel and fuel additives as well as oxidising and reducing agents. EPA’s Chemical Data-Reporting (https://www.epa.gov/chemical-information)

Additionally, BF3 (Boron Trifluoide) is used by the paper sector to manufacture pulp.

Additionally, it can be utilised in engines, braking fuels, and oils as a lubricant. Besides that, it can be used to make crude oil and refined petroleum products including fuel oils, drilling oils, and more.

As an organic synthesis catalyst, BF3 (Boron Trifluoride) is the most widely used BF3 in industrial operations. The following are some of them:

Alkylation processes by Friedel-Crafts

Ether-to-alcohol cleavage

Reactions of esterification

“Aromatic Compounds: Sulfonation and Nitration” by RJ Brotherton and colleagues, in the seventh edition of Ullmann’s Encyclopedia of Industrial Chemistry (1999-2012).

We’ve covered the basics of polarity and nonpolarity, as well as the unique properties of BF3 (Boron Trifluoride), which makes it nonpolar.

If you have any questions or concerns, feel free to post them in the comments section below. As quickly as we can, we’ll get back to you.

Read more: What is the polarity of PH3?

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.


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