Is Br2 polar or nonpolar? - Polarity of Br2
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 molecule||Bromine (Br2)|
|Bond type||Non-polar covalent|
|Polar or Non-polar?||Non-polar|
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.
The following three factors influence the polarity of any covalent molecule:
- 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
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||Electronic configuration||Valence electrons|
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.
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.
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.
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.
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.
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.
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 molecule||Non-polar molecule|
|Atoms must have a difference in|
|Atoms may have the same or different electronegativity values|
|Unequal charge distribution overall||Equal charge distribution overall|
|Net dipole moment greater than zero||Net 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 –
- How to tell if a molecule is polar or nonpolar?
- Is F2 polar or nonpolar?
- Is CH2Cl2 polar or nonpolar?
- Is CH3F polar or nonpolar?
- Is NCl3 polar or nonpolar?
- Is NO3– polar or nonpolar?
- Is BrF5 polar or nonpolar?
- Is SF4 polar or nonpolar?
- Is CO2 polar or nonpolar?
- Is NH3 polar or nonpolar?
- Is SO2 polar or nonpolar?
- Is SO3 polar or nonpolar?
- Is H2O polar or nonpolar?
- Is H2S polar or nonpolar?
- Is HCN polar or nonpolar?
- Is CCl4 polar or nonpolar?
- Is XeF4 polar or nonpolar?
- Is CH2O polar or nonpolar?
- Is CHCl3 polar or nonpolar?
- Is SF6 polar or nonpolar?
- Is BF3 polar or nonpolar?
- Is PCl5 polar or nonpolar?
- Is CH3Cl polar or nonpolar?
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.
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.
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
∴ 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.
- 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).
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