Chlorine fluoride is a diatomic compound represented by the chemical formula ClF. At room temperature, ClF exists as a volatile colorless gas. It is also known as chlorine monofluoride.
This interhalogen compound is used as a fluorinating agent. ClF is an extremely reactive compound and destroys glass instantly.
Many students are confused about the polarity of chlorine fluoride (ClF). So, is ClF polar or non-polar? Let’s find out.
Is ClF polar or non-polar?
Chlorine monofluoride (ClF) is a polar molecule. Both chlorine and fluorine share one electron, each forming a single covalent bond, leading to a linear molecule.
The electronegativity of the fluorine (F) atom is greater than the chlorine (Cl) atom. The F atom strongly attracts the shared electron pair in the Cl-F bond.
Thus, the Cl-F bond in the ClF molecule is polar and possesses a specific dipole moment value.
The electronegativity difference causes a partial positive charge (δ+) on the Cl atom and a partial negative (δ–)charge on the F atom. As a result, the Cl-F bond has a dipole moment value. Thus, ClF is a polar molecule with a dipole moment equal to 0.887 D.
In chemistry, a molecule with unequal charge distribution between different centres of bonded atoms is a polar molecule.
It is formed by the covalent bond between two different atoms leading to an asymmetric
electron density.
In this case, the atoms acquire partial positive (δ+) and partial negative (δ–) charges.
If the dipole moments of individually polar bonds are not canceled, the molecule will be polar, such as ClF.
Hence a polar molecule has an unequal distribution of the electronic charge. Contrarily, if the electronic charge is evenly distributed over the molecule, in that case, it will be a non-polar molecule overall.
The following three factors influence the polarity of any covalent molecule:
Electronegativity.
Dipole moment.
Molecular geometry or shape.
How do these factors lead to the polarity of the ClF molecule? Continue reading to find out.
Factors affecting the polarity of ClF
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.
Greater the electronegativity difference between bonded atoms in a molecule, the higher the bond polarity.
Both fluorine and chlorine belong to group VII-A (or 17) of the Periodic Table. The electronic configuration of chlorine is 1s22s22p6 3s2 3p5, so it has 7 valence electrons for bonding.
On the other hand, the electronic configuration of fluorine is 1s22s22p5. Thus, the F atom also has 7 valence electrons. The F and Cl atoms thus form a single covalent bond to complete their octet configuration.
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 F and Cl atom in the ClF molecule.
Atom
Electronic configuration
Valence electrons
Fluorine (9F)
1s22s22p5
7
Chlorine (17Cl)
1s22s22p6 3s2 3p5
7
According to Pauling’s scale, a molecule is polar if there is an electronegativity difference of 0.5 to 1.7 units between the bonded atoms.
The electronegativity of fluorine is more than chlorine (E.N of F = 3.98, E.N of Cl = 3.16). There is an electronegativity difference of 0.82 units between these two bonded atoms.
Due to this electronegativity difference, fluorine strongly attracts the shared electron cloud from the Cl-F bond in the ClF molecule. The bonded electrons are held significantly close to the fluorine.
The Cl-atom thus gains a partial positive (Clδ+) charge, while the fluorine atom being more electronegative, obtains a partial negative (Fδ-) charge.
In this way, oppositely charged poles develop in the ClF molecule. Thus, ClF is a polar molecule.
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.
The dipole moment of the Cl-F bond points from Clδ+ to Fδ- due to the electronegativity difference between the bonded Cl and F atoms.
Thus, the Cl-F bond in the ClF molecule is polar, with a net dipole moment greater than zero.
Molecular geometry
As discussed earlier, a chlorine monofluoride (ClF) molecule consists of a single Cl-F covalent bond. The overall molecule consists of a total of 14 valence electrons. There are three lone pairs of electrons on each F and Cl atom.
According to the Valence Shell Electron Pair Repulsion Theory (VSEPR) theory of chemical bonding, ClF is an AXN3-type molecule. The ideal electronic geometry of the ClF molecule is tetrahedral with 4 electron pairs around the chlorine atom.
However, there is only one bond pair in the actual ClF molecule with a total of six lone pairs of electrons (3 pairs on each Cl and F atom). The molecule thus adopts a linear shape to minimize the electronic repulsions due to the lone pairs of electrons.
As a result of the electronegativity difference, the Cl-F bond has a dipole moment value in the chlorine fluoride (ClF) molecule. There is a non-uniform electronic charge distribution over the molecule.
In conclusion, ClF is a polar molecule with a net dipole moment value of 0.887 D.
Difference between polar and nonpolar?
Polar molecule
Non-polar molecule
Atoms must have a difference in
electronegativity
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), chlorine fluoride (ClF), iodine trichloride (ICl3), bromine pentafluoride (BrF5), etc.
Examples include oxygen (O2), nitrogen (N2), methane (CH4), carbon disulfide (CS2), etc.
ClF has a polar covalent bond because of an electronegativity difference between bonded F and Cl atoms.
The Cl-atom gains a partial positive (Clδ+) charge, while the fluorine atom obtains a partial negative (Fδ-) charge.
The linear molecule has a dipole moment value equal to 0.887 D.
Thus, ClF is polar in nature.
Which is more polar, ClF or BrF?
The greater the electronegativity difference, the higher the bond polarity, resulting in a high dipole moment value.
ClF has an electronegativity difference of 0.82 units between the bonded F and Cl atoms. The linear molecule has a dipole moment equal to 0.887 D.
BrF has an electronegativity difference of 1.02 units between the bonded F and Br atoms. The linear molecule has a dipole moment equal to 1.42 D.
Thus, BrF is molar polar than ClF.
Is chlorine fluoride (ClF) acidic or basic?
The ClF molecule can act as a lewis acid and a lewis base.
Due to six lone pairs of electrons in total, this molecule can donate electrons to other compounds. Hence, acting as a lewis base.
The molecule can also accept electrons from other species as the Cl atom has a vacant d-orbital. Hence, acting as lewis acid.
Thus, ClF can act as an acid as well as a base.
Is there a formal charge on the bonded atoms in the ClFmolecule?
Formal charge of an atom = [ valence electrons – non-bonding electrons- ½ (bonding electrons)]
For chlorine atom
Valence electrons = 7
Bonding electrons = 2
Non-bonding electrons = 6
∴ The formal charge on the chlorine atom = 7-6-2/2 = 1-1 = 0
For fluorine atom
Valence electrons = 7
Bonding electrons = 2
Non-bonding electrons = 6
∴ The formal charge on the fluorine atom = 7-6-2/2 = 1-1 = 0
Thus, no formal charge is present on the chlorine monofluoride (ClF) molecule.
Summary
Chlorine fluoride (ClF) is a polar molecule.
It consists of a polar Cl-F bond due to an electronegativity difference of 0.82 units between the bonded atoms.
The fluorine atom is more electronegative and strongly attracts the shared electron cloud from the Cl-F bond.
There are three lone pairs of electrons on each Cl and F atom in the linear-shaped molecule.
Due to the electronegativity difference, the Cl-F bond has a dipole value, and poles are formed in the molecule. Thus, ClF is polar in nature (μ = 0.887 D).
Vishal Goyal is the founder of Topblogtenz, a comprehensive resource for students seeking guidance and support in their chemistry studies. He holds a degree in B.Tech (Chemical Engineering) and has four years of experience as a chemistry tutor. The team at Topblogtenz includes experts like experienced researchers, professors, and educators, with the goal of making complex subjects like chemistry accessible and understandable for all. A passion for sharing knowledge and a love for chemistry and science drives the team behind the website. Let's connect through LinkedIn: https://www.linkedin.com/in/vishal-goyal-2926a122b/
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