Is Br2 polar or nonpolar? - Polarity of Br2

Home > Chemistry > Br2 polar or nonpolar?

is br2 polar or nonpolar

Bromine is a highly toxic diatomic liquid compound represented by the chemical formula Br2. It exists as a volatile brownish-red liquid with a sharp odour at room temperature.

Bromine is the only element other than mercury in the liquid state at standard temperature and pressure. The name bromine comes from the Greek word “Bromos”, which means stench (unpleasant smelling).

This article will discuss a very important property of bromine (Br2), i.e., its polarity. So, is Br2 polar or non-polar? Continue reading to find out.

Is Br2 polar or non-polar?

Bromine (Br2) is a non-polar molecule. The Br-Br bond in the Br2 molecule is non-polar due to no electronegativity difference between the bonded atoms.

As the Br2 molecule contains two same atoms and there is no difference in electronegativity between the two atoms, the electronic charge is evenly distributed over the molecule.

Due to this, the Br-Br bond in the Br2 molecule is non-polar and possesses no dipole moment value.

Thus, the symmetric, linear Br2 molecule is non-polar with a net dipole moment equal to 0.

Name of moleculeBromine (Br2)
Bond typeNon-polar covalent
Molecular geometryLinear
Polar or Non-polar?Non-polar
Dipole momentZero
Bond angle180°

What is a polar and non-polar molecule?

A molecule with an equal charge distribution between different centers of bonded atoms is a non-polar molecule.

It is formed by the covalent bond between two same atoms leading to a symmetric electron density in the molecule, such as the Br2 molecule.

In the case of asymmetric molecules, If the dipole moments of individually polar bonds are canceled, the molecule will be non-polar.

Hence, a non-polar molecule has an equal distribution of the electronic charge. Contrarily, if the electronic charge is not evenly distributed over the molecule, in that case, it will be a polar molecule.

Polar vs nonpolar molecule

The following three factors influence the polarity of any covalent molecule:

  • Electronegativity.
  • Dipole moment.
  • Molecular geometry or shape.

In the next section, we will uncover how these factors lead to the non-polar nature of the bromine (Br2) molecule. Continue reading.

Factors affecting the polarity of Br2

Electronegativity

It is defined as the ability of an atom to attract a shared pair of electrons from a covalent chemical bond.  

Electronegativity decreases down the group in the Periodic Table of elements while it increases across a period.

It is directly related to the polarity of any molecule. The greater the difference in electronegativity between atoms in a molecule, the higher will be the bond polarity.

Bromine belongs to group VII-A (or 17) of the Periodic Table. The electronic configuration of bromine is [Ar] 3d104s24p5, so it has 7 valence electrons for bonding.

Thus, the two Br atoms form a single covalent bond to complete their octet configuration in the Br2 molecule.

One valence electron consumed in bonding out of the seven initially available leaves behind six valence electrons, i.e., three lone pairs of electrons on each Br atom in the Br2 molecule.

atom present in Br2

AtomElectronic configurationValence electrons
Bromine (35Br)1s22s22p63s23d104s24p57

According to Pauling’s electronegativity scale, a molecule is non-polar if there is an electronegativity difference of 0 units between the bonded atoms.

The electronegativity of the bromine atom is 2.96 on Pauling’s scale. There is no difference in electronegativity between the same bonded atoms in the Br2 molecule.

bonds in Br2 nonpolar because of equal sharing of electrons

Due to the zero electronegativity difference, there is a uniform electronic charge distribution in the Br2 molecule overall. As a result, no charged poles are developed in the Br2 molecule.

Thus, the Br-Br bond is non-polar in Br2 molecule.

Br-Br bond is nonpolar in Br2

Dipole Moment

The dipole moment is the product of electrical charge (Q) and bond length (r) between two bonded atoms. It is a vector quantity expressed in Debye (D) units.

It is represented by a Greek symbol µ and measures the polarity of a bond.

The dipole moment of any molecule depends on the difference in electronegativity between the bonded atoms. The greater the electronegativity difference, the higher the bond polarity, resulting in a high dipole moment value.

It points from the partial positive (δ+) center to the partial negative (δ) center of a bond or molecule.

dipole moment representation

As the Br2 molecule constituents the atoms of the same element (Br), there is no difference in electronegativity between the bonded atoms. Due to this, the net dipole of the Br-Br bond is zero in the Br2 molecule.

As a result of the zero dipole moment of the Br-Br bond, the Br2 molecule is non-polar.

dipole moment of Br2

Molecular geometry

As discussed earlier, a bromine (Br2) molecule consists of a single Br-Br covalent bond. The overall molecule consists of a total of 14 valence electrons. There are three lone pairs of electrons on each Br atom.

what is Br2 lewis structure

The molecule adopts a linear shape to minimize the repulsion effects due to the lone pairs on each Br atom. There is a bond angle of 180 degrees.

Why is Br2 nonpolar

Due to no electronegativity difference between the bonded atoms, the only Br-Br bond has no dipole moment value in the bromine (Br2) molecule. There is an equal charge distribution over the molecule.

Thus, bromine (Br2) is a non-polar molecule with a zero dipole moment.

Difference between polar and nonpolar?

Polar moleculeNon-polar molecule
Atoms must have a difference in
electronegativity
Atoms may have the same or different electronegativity values
Unequal charge distribution overallEqual charge distribution overall
Net dipole moment greater than zeroNet dipole moment equals to zero
Examples include water (H2O), ethanol (CH3CH2OH), ammonia (NH3), sulfur dioxide (SO2), bromine trifluoride (BrF3), nitric oxide (NO), bromine pentafluoride (BrF5), etc.Examples include oxygen (O2), nitrogen (N2), fluorine (F2), bromine (Br2), methane (CH4), sulfur trioxide (SO3), etc.

Also, check –

FAQ

Why is Bromine (Br2) a non-polar molecule?

Br2 has a non-polar covalent bond because there is no electronegativity difference between bonded Br atoms.

  • There is a uniform distribution of the electron cloud over the Br2
  • The linear molecule has a dipole moment value equal to zero.

Thus, bromine (Br2) is a non-polar molecule.

Hydrogen (H2) and bromine (Br2) are non-polar, while hydrogen bromide (HBr) is polar. How?

Hydrogen (H2) and bromine (Br2) are non-polar because there is no electronegativity difference between bonded atoms in each molecule.

There is a uniform distribution of the electron cloud over both. Thus, H2 and Br2 are non-polar with zero dipole moment value.

Hydrogen bromide (HBr) is a polar molecule because of an electronegativity difference of 0.76 units between the bonded H and Br atoms.

There is a non-uniform distribution of the electron cloud over the HBr molecule.

Thus, HBr is polar with a dipole moment value of 0.79 D.

polarity of Br2 vs H2 vs HBr

Bromine (Br2), a non-polar molecule, is soluble in water (H2O), a polar solvent. How?

Although bromine has a non-polar Br-Br bond, it is slightly soluble in water.

This behavior can be explained by the polarizing ability of the large-size Br2 molecule in the presence of water.

The water molecule can induce a dipole on the Br2 molecule, leading to the miscibility of Br2 with water.

Thus, Br2 is slightly soluble in water due to the dipole-induced dipole interactions.

Is there a formal charge on the bonded atoms in the Br2 molecule?

Formal charge of an atom = [ valence electrons – non-bonding electrons- ½ (bonding electrons)]

For bromine atoms

  • Valence electrons = 7
  • Bonding electrons = 2
  • Non-bonding electrons = 6

∴ The formal charge on the bromine atoms  = 7-6-2/2 = 1-1  = 0

Thus, no formal charge is present on the bromine (Br2) molecule.

Summary

  • Bromine (Br2) is a non-polar molecule.
  • It consists of a single non-polar Br-Br bond due to an electronegativity difference of 0 units between the bonded atoms.
  • The electronic charge is evenly distributed over the molecule due to no electronegativity difference between the same atoms.
  • There are three lone pairs of electrons on each Br atom in the linear-shaped molecule.
  • The Br-Br bond angle is 180 °, and the bond length is 228 pm.
  • Due to the zero electronegativity difference, the Br-Br bond has no dipole moment value, and no poles are formed in the molecule.
  • In conclusion, the linear Br2 molecule is non-polar (μ =0).
Did you like it?

About the author

topblogtenz author

My name is Vishal Goyal and I am the founder of Topblogtenz. I hold a degree in B.tech (Chemical Engineering) and have a strong passion for the life sciences and chemistry. As a highly qualified and experienced chemistry tutor with 4 years of experience, I possess a deep understanding of the unique challenges that students often encounter when attempting self-study in the field of chemistry. I have created this website as a comprehensive resource for those who are seeking guidance and support in their chemistry studies. I have brought together a team of experts, including experienced researchers, professors, and educators, to provide our readers with accurate and engaging information on a wide range of chemistry and science topics. Our goal is to make complex subjects like chemistry accessible and understandable for all. I hope you find the information and resources on our site helpful in your studies. Let's connect through LinkedIn: https://www.linkedin.com/in/vishal-goyal-2926a122b/

Share it...

Leave a Comment

Your email address will not be published. Required fields are marked *

Copyright © 2023 - topblogtenz.com. All rights Reserved

Scroll to Top