Best Overview: Is HBr Polar or Nonpolar? - Science Education and Tutorials

Bromine compounds are very different in nature. Hydrogen bromide has the chemical formula HBr. Hydrogen is the first element in the periodic table and bromine comes in the halogen family. Another name for this chemical compound is hydrobromic acid. Students used to ask “Is HBr polar or nonpolar?”, “HBr Lewis Structure”, “HBr molecular geometry”, “HBr bond angle”, and “HBr polarity”. In this blog post, we are going to discuss the polarity of HBr in a detailed manner.

HBr is commonly appearing at ordinary temperatures and pressures, it exists as a liquid with a slight brownish texture, containing 68.85 percent HBr by weight. HBr contains one hydrogen atom and one bromine atom. Hydrogen bromide (HBr) is corrosive to biological tissue and metals, and it can also cause huge damage when it comes into contact with wood, cotton, and other materials. The bromine atom stays one terminal of the molecule and the remaining one hydrogen atom in another terminal. “Is HBr polar or nonpolar?”, to answer this question, we need a detailed analysis of the polarity of the HBr molecule.

Because of the linear form of hydrogen bromide(HBr). Bromine has atomic number 35 in the modern periodic table and seven outermost valence shell electrons. It comes under the halogen family group in the periodic table. Similarly, hydrogen has atomic numbers one and one outermost valence shell electron.

HBr molecule is formed by elements of the hydrogen and halogen family group in the periodic table. When HBr acid is exposed to air, it absorbs water quickly and produces white vapors that have a distinct odor, irritate the skin, and are toxic to breathe. Hydrogen bromide (HBr) can generate dilute acid when it diluted with water and acts as a brominating agent in organic synthesis.

Is HBr polar or nonpolar, then? HBr (hydrogen bromide) is polar due to unequal electronegativity values of atoms in the HBr molecule. Second, the difference in electronegativity between hydrogen and bromine atoms causes the H-Br bonds to become polar, causing the entire molecule to become polar as well, resulting in a net dipole moment of the HBr molecule is 2.60 D.

Table of Contents

Preparation of HBr

Hydrogen bromide(HBr) is a slight brownish liquid with a strong intense odor. It is prepared primarily through the acidification of bromide salt. It is the heterogeneous reaction, potassium bromide in the solid phase and concentrated sulfuric acid in the liquid phase. Initially, potassium bromide reacted with concentrated sulfuric acid formed the hydrogen bromide(HBr). This acidification of the bromide salt reaction step is exothermic in nature.

The chemical equation of acidification of bromide salt exothermic reaction is shown below.

KBr + H2SO4 ——Exothermic—-> KHSO4 + HBr
Preparation of hydrogen bromide(HBr)

HBr Molar Mass Calculation

HBr has a molecular mass of 80.9119 g/mol, which may be computed as follows.

Mol mass of HBr = 1 * 79(atomic mass of Br) + 1* 1(atomic mass of H) = 80.9119 g/mol.
HBr molar mass calculation

The chemical composition of the hydrogen bromide molecule is one bromine atom and one hydrogen atom in the linear structure form.

HBr Lewis Structure: Is HBr polar or nonpolar?

One terminal atom is bromine, which is flanked by one hydrogen atom. A bromine atom contains seven outermost valence electrons, which means it contains seven electrons in its outermost shell, whereas hydrogen has one outermost electron. A bromine atom is required one electron to complete the octet of bromine atoms. If you want to know about the octet rule, please see in our previous post.

As a result of this, both one bromine atom forms covalent bonds with the hydrogen atom, leaving the two atoms with a linear structure. The bond pairs of H-Br are not repelled by the lone pairs on the bromine atom. According to VSEPR theory, no electronic repulsion causes the HBr molecule’s shape to linear structure, similar to that of the NO2+ ion.

The bond pair forces both H-Br bond linear and polarize in nature, resulting in the linear form of the HBr molecule. Because they generate no electrical repulsion among the HBr molecule, no lone pairs have deformed shapes of the HBr molecule.

Electronegative difference calculation HBr:

When it comes to the electronegativity value of the HBr molecule, bromine has an electronegativity of 2.96, while hydrogen has an electronegativity of 2.2. The electronegativity difference can be calculated by the following method.

Electronegativity value of bromine = 2.96
Electronegativity value of hydrogen = 2.2
Difference of electronegativity value between bromine and hydrogen = 2.96 – 2.2=0.76
Electronegativity difference calculation of HBr molecule

The H-Br bond of the HBr molecule becomes polar in nature due to this difference in electronegativity value. The power with which an atom can attract bound electron pairs towards its side is known as the electronegativity of the atom.

As a result of this, the dipole moment of the H-Br bond is non zero, and the dipoles of the H-Br bond are not negated due to the linear structure. The total dipole moment of the HBr molecule is calculated to be 2.60 D. Bromine atom receives a partial negative charge on it, while hydrogen atom receives a partial positive charge on it.

HBr molecule’s electron dot structure is also known as HBr Lewis structure. It determines the number of outermost valence electrons and the electrons involved in the formation of the HBr molecule’s bonds. When discussing the Lewis structure of the HBr molecule, it is necessary to understand the outermost valence electrons of HBr.

The hydrogen atom is on one terminal of the HBr molecule, with one electron in its outermost valence electron shell, while the bromine atom is the outermost valence electron shell, with seven electrons and one electron missing in the shell to complete its octet.

As a result of this above explanation, the HBr molecule contains a total of 8 valence electrons. The one hydrogen atom establishes covalent connections with the bromine atom, leaving the HBr molecule with a linear structure form.

The lone pairs of bromine atoms cause no repulsion with H-Br bond pairs, causing the H-Br bonds to form a linear structure and the shape of the molecules to like that of the NO2+ (nitronium ion) molecule. The H-Br bond has a bond angle of roughly 180 degrees. H-Br bond has a bond length of 141 pm (picometer).

To sketch the HBr Lewis structure by following these instructions:

Step-1: Determine the total number of outermost valence shell electrons in the HBr molecule. The first step is to figure out how many outermost valence shell electrons there are in the HBr Lewis structure. A valence electron is one of an atom’s outermost shell electrons. In the Lewis diagram, it is represented by dots. The bromine atom of the HBr molecule can be represented as follows.

Look for the periodic group of each atom in HBr to determine its valence electron. Hydrogen and bromine are both members of the hydrogen and halogen family, which is the 1st and 17th groups in the periodic table respectively. Bromine and hydrogen have seven and one valence electrons in their outermost shell respectively.

Because hydrogen and bromine belong to the hydrogen and halogen family group in the periodic table, their valence electrons are one and seven respectively.

Total outermost valence shell electron of bromine atom in HBr = 7
Total outermost valence shell electron of the hydrogen atom in HBr= 1
The HBr molecule has one terminal hydrogen atom and one bromine atom. Then the total outermost valence shell electrons can be calculated as follows
∴ Total outermost valence shell electrons available for HBr Lewis structure( dot structure) = 7 + 1*1 = 8 valence electrons in HBr
calculation of total valence electron of HBr molecule

Step-2: The HBr molecule contains only two atoms. Locate the atom with the least electronegative charge and place it in the two terminals of the HBr molecular geometry. In this phase, we’ll select the least electronegative atom in the HBr molecule to place in the Lewis structure diagram’s one terminal. In the periodic table, the electronegativity value increases in order from left to right and decreases in order from top to bottom in periodic groups.

As a result, bromine is the third atom in the halogen family group in the periodic table. Hydrogen comes first in the hydrogen family group. A hydrogen atom has a lower electronegative value than a bromine atom. Furthermore, because bromine is the most electronegative element in chemistry, it can be another terminal atom in a HBr Lewis structure diagram. As a result of this, place hydrogen at one terminal of the HBr Lewis structure, with a bromine atom in another terminal of a linear molecule.

Step-3: Use one single bond (H-Br) to connect the outside and core atoms in the HBr molecule. Connect the outside atom (bromine) to the other terminal atom (hydrogen) with one single bond in this stage.

Count how many outermost valence shell electrons we’ve used so far in the HBr structure. Because each hydrogen atom is connected to a bromine atom by one single (H-Br) bond, each connection contains two electrons. Those is called bond pairs.

So, from the total of 8 valence electrons available for the HBr Lewis structure, we employed 2 electrons for one single (H-Br) bond in the HBr molecule. There are still 6 valence electrons left in the HBr molecule. Where do we need to place them in HBr molecular geometry?

Step-4: Starting with the terminal bromine atoms in the HBr molecule, place the remaining valence electrons. We always start inserting valence electrons from the exterior atom first in the HBr Lewis structure diagram. As a result, first, wrap around the leftover valence electrons on the bromine atom.

To complete its octet, bromine requires 8 electrons in its outermost valence shell. With the help of a single bond, bromine already shares one electron and another one from a hydrogen atom. Put 6 electrons around the terminal bromine atom and you’re done with the bromine in the HBr molecule.

In the HBr molecule structure above, we’ve put 6 electrons around the bromine atom, represented by a dot. As the bromine atom has 8 electrons in its outermost valence shell, the bromine atom comfortably completes its octet stability in the HBr molecule.

Using the HBr Lewis structure, count how many outermost valence shell electrons have been consumed so far. In the HBr molecular structure, 8 electrons are represented as dot structure, whereas one single bond contains 2 electrons. As an outcome of the calculation, the outermost valence shell electrons are 6 + 2 = 8.

So far, we’ve used 8 of the total 8 outermost valence shell electrons available for the HBr Lewis structure. Bromine is obeying the rule of the octet as 8 electrons around it. Place the six valence electrons around the bromine center atom, which is acting as an octet stabilization in this case.

What are HBr electron and molecular geometry?

HBr has a linear molecular geometry and like NO2+ ion electron geometry, according to the VSEPR theory. Because the terminal atom, bromine, has one H-Br bond with other terminal hydrogen atoms. In the same plane, the H-Br bond forms a 180-degree angle. Because two atoms are in the same plane, they form a linear molecular shape.

At that plane, there are no lone pairs of electrons in the HBr molecule. It maintains the linear structural form after connecting the bromine and hydrogen atoms to the linear form. The two atoms are located just opposite bond pairs in the linear molecular geometry. The two atoms of the HBr are just linear form and bond pair plane in the molecular geometry.

Because of the two atoms of the HBr molecule, it gives linear electron geometry. But the HBr molecular geometry is a linear form in nature. It is the asymmetrical geometry of the HBr molecule. That makes, HBr molecule is polar.

How to find HBr molecular geometry

Determine the number of lone pairs on the HBr Lewis structure.
We need to figure out how many lone pairs there are on the terminal bromine atom of the HCl Lewis structure because the lone pairs on bromine are primarily responsible for the HBr molecule geometry distortion.

Use the formula below to find the lone pair on the HBr molecule’s terminal bromine atom.
L.P(Br) = V.E(Br) – N.A(Br-H)/2

Lone pair on the terminal bromine atom = L.P(Br)
The core terminal bromine atom’s valence electron = V.E(Br)
Number of Br-H bonds = N.A (Br-H)
calculation for Bromine atom lone pair in HBr molecule

In the case of HBr, the terminal atom, bromine, has seven outermost valence shell electrons and one hydrogen atom connected to it.

As a result of this, L.P(Br) = (7 – 1)/2=3

The lone pair on the terminal bromine atom of the HBr electron geometry structure is equal to three. It means, the terminal bromine atom contains three lone pairs.

Determine the number of HBr molecular hybridizations.
How to find the hybridization of the HBr molecule?. Now we need to figure out what HBr’s molecular hybridization number is.

The formula of HBr molecular hybridization is as follows:
No. Hyb of HBr = N.A(Br-H) + L.P(Br)
No. Hy of HBr= the number of hybridizations of HBr
Number of H-Br bonds = N.A (Br-H)
Lone pair on the terminal bromine atom = L.P(Br)
Calculation for hybridization number for HBr molecule

Bromine, then, is a terminal atom with one hydrogen atom linked to it and three lone pairs in the HBr molecule. Then the number of hybridization of HBr (No. Hyb of HBr) can be calculated as follows

No. Hyb of HBr = 1+3 =4

The number of hybridization for HBr molecule is four. one S orbital, and three p orbitals combine together to form the sp3 hybridization. HBr molecule is SP3 hybridized.

3. Use VSEPR theory to determine HBr molecular geometry shape

When the VSEPR theory is utilized to calculate the shape of the HBr molecule, the AXN approach is typically used.

The AXN notation is as follows:
The terminal bromine atom in the HBr molecule is denoted by the letter A.
The bound pairs (H-Br) of electrons to the terminal atom are represented by X.
The lone pairs of electrons on the terminal bromine atom are denoted by the letter N.
Notation for HBr molecular geometry

We know bromine is the terminal atom with one bound (H-Br) pairs of electrons and three lone pairs. because of the HBr Lewis structure. HBr has the general molecular geometry formula AXN3.

If the molecule has an AXN3 generic formula, the molecular geometry will be linear form and the electron geometry will be linear, according to the VSEPR theory.

Name of Molecule	Hydrogen bromide
Chemical molecular formula	HBr
Molecular geometry of HBr	Linear
Electron geometry of HBr	Linear
Hybridization	Sp³
Bond angle (H-Br)	180º degree
Total Valence electron for HBr	8
The formal charge of HBr on Bromine	0

How to calculate the formal charge in HBr Lewis Structure?

The formal charge on the terminal bromine atom of the HBr molecule often represents the actual charge on that bromine terminal atom. The formal charge will be found on the terminal bromine atom of the HBr Lewis dot structure in the following calculation.

To calculate the formal charge on terminal bromine atom of HBr molecule by using the following formula:
The formal charge on bromine atom of HBr molecule= (V. E(Br)– L.E(Br) – 1/2(B.E))
V.E (Br) = Valence electron in bromine atom of HBr molecule
L.E(Br) = Lone pairs of an electron in bromine atom of HBr molecule.
B.E = Bond pair electron in Br atom of HBr molecule
calculation of formal charge on bromine atom in HBr molecule

We have 7 valence electrons, 6 lone pair electrons, and two bonding electrons in the bromine terminal atom (one single bond attached to hydrogen) of the HBr molecule. Now put these value of the bromine atom in the above formula

Formal charge on bromine atom of HBr molecule = (7- 6-(2/2)) =0

The formal charge on terminal bromine atom of HBr Lewis structure is zero.

Lewis structure of some other related post in this blog. See more detail by clicking on it, H2O, BeCl2, SF4, NH3, XeF4, BF3, BrF3, BrF5, SO3, SCl2, SO3, PCl3, H2S, NO2+, and CH2Cl2 molecules.

Dipole moment of HBr

The dipole moment of the HBr molecule can assist us in determining the polarity’s strength. The polarity of any molecule is proportional to its dipole moment. Because the form of HBr is asymmetric. The dipole moment of HBr does not cancel each other as a result of this.

Dipole moment of HBr can be calculated as follows
D(H-Br) = Q(H-Br) * R(H-Br)
D(H-Br) = Dipole moment of H-Br bond in HBr molecule
Q(H-Br) = Charge distribution in Br and H atom of HBr molecule
R(H-Br)= Bond length of H-Br bond in HBr molecule
Dipole moment calculation of HBr molecule

Net dipole moment of HBr molecule is 2.60 D.

Why is HBr a polar molecule?

Due to the existence of three lone pairs on the bromine atom, the hydrogen bromide (HBr) molecule has a linear geometrical form. According to the VSEPR hypothesis, lone pairs and bond pairs did not repel each other, causing the H-Br bonds to form a linear molecular structure, resulting in a linear shaped molecule.

The dipole moment of H-Br bonds does not cancel out as it does in asymmetric linear HCl molecules. HBr has a dipole moment of 2.60 D across the entire molecule. The formation of a polar molecule is caused by the geometrical asymmetrical structure and the difference in electronegativity value of atoms in the HBr molecule.

Because of the asymmetric shape of the HBr molecule, the charge is dispersed non-uniformly among the hydrogen and bromine atoms, resulting in the formation of positive and negative terminal poles across the HBr molecule.

Properties of HBr molecule

The properties of HBr molecule are listed as follows

It has the appearance of a colorless gas and liquid.
It dissolves easily in water and gives hydrobromic acid.
The HBr molecule has a density of roughly 1.49 g/cm3.
The hydrogen bromide molecule’s molecular mass is calculated to be 80.9119 g/mol.
HBr has a melting point of 86.9 °C (124.4 °F).
HBr has a predicted boiling point of roughly 66.8 °C (88.2 °F).
At room temperature, it produces a harsh, unpleasant odour.

Uses of HBr molecule

HBr molecule uses are listed as follows

It’s commonly employed as a catalyst and reagent in a wide range of organic processes.
Because anhydrous hydrobromic acid is a hazardous substance, it is transported in high-pressure cylinders.
It also serves as a bridge between two different compounds.
It is widely used in the manufacture of sanitizers and disinfectants.

Conclusion

Due to the existence of three lone pairs on the terminal bromine atom, hydrogen bromide has a linear structural form. With a bond angle(H-Br) of roughly 180 degrees, the bromine atom is the one terminal, another side by one hydrogen atom. Its electron geometry is linear. The molecular hybridization of the HBr molecule is sp3.

Because of the difference in electronegativity between hydrogen and bromine atoms, the H-Br bond is polar, and the entire molecule has a dipole moment of 2.60 D. This is due to the unsymmetrical structure of the HBr molecule with three lone pairs in a terminal bromine atom. The HBr molecule is polar due to its asymmetric geometrical shape and unequal electronegativity of its atoms.

If you have any queries and doubts about this HBr polarity post, please leave your question in the comment section. We shall reply back on it as soon as possible.

FAQ on “Is HBr polar or nonpolar?”

Is HBr a polar or nonpolar molecule?

Because of the electronegativity value difference between hydrogen atom (2.2) and bromine atom (2.96), hydrogen bromide (HBr) is a polar molecule (dipole moment 2.60 D). Bromine is more electronegative than hydrogen, thus it pulls electrons from hydrogen, resulting in the formation of two dipole poles and a net dipole moment for the molecule.

What kind of bond is HBr?

HBr forms covalent polar bond. Bromine atom pull the bonding pair of electron towards its side, so it becomes slight negative side. Then hydrogen atom become slightly positive in charge. Electron density cloud moves to bromine atom in the HBr molecule