Polar or nonpolar, BrF5?

When it comes to the polarity of a molecule, the first question that comes to mind regarding BrF5 or (Bromine Pentafluoride, as it is commonly called) is whether it is polar or non-polar. As in Chemistry, the two primary kinds of molecules are classified as polar and non-polar.

Most molecules may be simply classified as polar or non-polar, however others are difficult to characterise in terms of polarity. Some molecules sit somewhere on the spectrum scale between the two categories. Consequently, a number of compounds, including BrF5, encounter this difficulty.

So, is BrF5 a polar or non-polar substance? BrF5, or Bromine Pentafluoride, is a polar molecule due to its square pyramidal molecular structure and asymmetric charge distribution that concentrates on the centre atom. A core bromine atom encompasses a total of five fluorides and forms a lone pair of electrons within the molecule. Consequently, this molecule should be polar.

This is a colourless, flammable liquid with a pungent odour that is used primarily as a fluorinating agent to generate fluorocarbons and as an oxidizer in rocket propellant systems. It is a highly hazardous chemical when inhaled.

It corrodes metals and biological tissue. It can increase the combustion of flammable substances.

Before delving deeper, let’s define a few terminology and other essentials as described in the subtopics that follow.

How can polar or non-polar molecules be distinguished?

This solution can be found using these terms:

Polarity is the distribution of electric charges surrounding atoms, molecules, and chemical groups.

When there is a difference in electronegativity between the bound atoms, polar molecules arise.

Non-polar molecules develop when electrons are equally distributed across the atoms in a diatomic molecule, or when the polar bonds in a larger molecule are able to cancel each other out.

When a Polar molecule forms is unknown.

Polar molecules develop when two atoms in a covalent connection do not share electrons equally.

Consequently, a dipole occurs, and a portion of the molecule acquires a tiny positive charge while the other acquires a slight negative charge.

Typically, this occurs when the electronegativity of each atom in the molecule is different.

Example: H2O, NH3, SO2

A fascinating essay about the polarity of SF2 is presented.

When a non-polar molecule forms is unknown.

Non-Polar molecules are formed when two atoms in a covalent link share electrons equally.

In a non-polar covalent bond, electrons are distributed uniformly. In general, if the difference in electronegativity between two atoms is smaller than 0.5, the bond is non-polar (which is not in the case of BRF5).

In addition, a molecule is completely nonpolar if it is composed of identical atoms.

When polar bond atoms are structured so that their electric charges can cancel one other out, non-polar molecules can also form.

He, H4, N2, CO2 are a few examples. Read the article about the polarity of CF4 to gain a better understanding.

In this regard, BrF5 is without a doubt Polar!

BrF5 Lewis dot structure

The polarity of BrF5 is best determined by first sketching a Lewis dot structure.

The Lewis structure of BrF5 has octahedral electron geometry and sp3d2 hybridization. Next, using the VSEPR rule, we will depict the three-dimensional structure of BrF5 in three dimensions.

Remember to sketch the lone pair of electrons, and you will observe the formation of something wonderful.

Bromine pentafluoride (BrF5) is a polar molecule as evidenced by the presence of an asymmetries in its charge distribution.

Why is the BrF5 molecule polar?

Bromine (Br) is a member of the halogen family and has a total of seven valence electrons.

Five of these electrons are shared with fluorine (F) atoms through covalent bonds, leaving two electrons to form a lone pair at the top of this molecule.

As the lone pair is an area with a higher negative charge, it becomes unbalanced because it lacks atoms with positively charged nuclei; hence, the molecule is determined to be polar.

Electronegativity: In terms of electronegativity, BrF5 consists of many polar covalent bonds, as the difference between the electronegativity of bromine (2.96 ) and fluorine (3.98 ), which is greater by.5 electronegativity, is substantial (even though both of them are halogens).

Typically, the reason why bromine is less electronegativity than fluorine is due to the number of layers of electrons sheltering the nucleus in (Br) and, consequently, lessening its average pull on its valence electrons.

Fluorine, on the other hand, does not have a large number of layers when internal electrons are considered; this may contribute to its shielding effect, indicating that it has a higher electronegativity than Br or bromine (in fact, it has the highest electronegativity of any element on the periodic table!).

Thus, the negative charge is unequally distributed!

What form of hybridization does BrF5 employ?

As seen in the initial diagram, the core bromine atom is surrounded by six electron groups: five bonding pairs and one lone pair.

In the majority of instances, the number of electron groups surrounding the core atom indicates that atom’s hybridization.

2 electron = sp

3 electron = sp²

4 electron = sp³

5 electron = sp³d

6 electron = sp³d²

BrF5 hence exhibits sp3d2 hybridization.

Why is BrF5 non-ionic and covalent?

As previously discussed, the difference in electronegativity between (Br) Bromine and (F) Fluorine is less than 1.7, hence it is not ionic.

This difference in electronegativity can only exist between a metal and a non-metal. Since all halogens are non-metals, BrF5 is not ionic.

Does BrF5 have a dipole moment?

(BrF5), also known as bromine pentafluoride, has a pyramidal structure depicted in the first picture.

PCl5, which has a trigonal bipyramidal shape, has no net dipole moment because the molecule is symmetrical about the central phosphorus atom.

However, BrF5 does possess a dipole moment due to its asymmetric structure, as depicted in the images.

BrF5 is it reactive?

Due to the presence of highly electronegative halogens in this molecule’s structure, it will react with a variety of organic compounds, including liquids such as water (H2O).

According to case studies conducted in the 1950s and 1960s, the presence of several halogens in the molecule BrF5 enabled it to be a highly powerful oxidant (capable of removing electrons from other molecules).

However, this resulted in later challenges in handling and conducting tests with this material that were required to be conducted in a safe and efficient manner.

Attributes of BrF5

In liquid form, boron pentafluoride appears pale yellow.

It has a density of roughly 2,466 g/cm3.

BrF5 has a low melting point of 61.30 °C or 78.34 °F and is consequently liquid at room temperature.

Its boiling point is 40.25 degrees Celsius, or 104.45 degrees Fahrenheit.

It has a molecular mass close to 174.9 g/mol.

It interacts aggressively with water.

Conclusion

The fact that the electronegativity difference between Br and F is more than 0.5 demonstrates that BrF5 is a polar molecule, as demonstrated above by a variety of examples and data (general electronegativity value).

Furthermore, the molecular shape of bromine pentafluoride is square pyramidal, which corresponds to an asymmetrical charge distribution on the central atom; hence, as demonstrated above, this molecule is polar.

We have also mentioned in this text that it is reactive and should thus be used with caution. However, it is mostly utilised in the aerospace industry for rocket propulsion. I hope this article was helpful!

Read more: Does Nickel Rust?

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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