ClF5 is the chemical formula of chlorine pentafluoride, also known as pentafluoro chlorine. It is a strong oxidant and was once considered an oxidizer for rockets. It is a colorless gas with a molar mass of 130.45 g/mol.
In this article, we will discuss the polarity of Penta fluoro chlorine ClF5. So, is ClF5 polar or non-polar?
Continue reading to find out.
Is ClF5 polar or non-polar?
Chlorine pentafluoride (ClF5) is a polar molecule. It consists of one chlorine (Cl) atom and five fluorine (F) atoms. The chlorine atom is kept at the central position while all the fluorine atoms are at the surrounding positions, making a square pyramidal molecular geometry.
An electronegativity difference of 0.82 units exists between the bonded atom of chlorine and fluorine in each Cl-F bond in ClF5. Thus, each Cl-F bond is individually polar in ClF5 and possesses a specific dipole moment value (symbol µ).
In the ClF5 molecule, the highly electronegative fluorine atom attracts the bonded electrons more strongly than the chlorine atom from each Cl-F bond. One lone pair of electrons is present on the central chlorine atom.
Due to the asymmetrical square pyramidal shape of the ClF5 molecule, the dipole moments of individually polar Cl-F bonds do not get canceled uniformly.
Hence, the charged electron cloud stays non-uniformly spread over the molecule. As a result, the ClF5 molecule is overall polar (net µ = 1.8 Debye).
A molecule is polar if there is a non-uniform charge distribution present in it.
If the charge distribution gets equally balanced in different parts, then that molecule or molecular ion is considered non-polar.
The following three factors mainly influence the polarity of a molecule:
The electronegativity difference between two or more covalently bonded atoms
Dipole moment
Molecular geometry or shape
Now, let us discuss the effect of the above three factors one by one to prove that the pentafluoro chlorine ClF5 is overall a polar molecule.
Factors affecting the polarity of ClF5
Electronegativity
It is defined as the ability of an elemental atom to attract a shared pair of electrons from a covalent chemical bond.
Electronegativity increases across a period in the Periodic Table while it decreases down the group.
Greater the electronegativity difference between bonded atoms in a molecule, the higher the bond polarity.
Chlorine (Cl) is present in Group 17 of the Periodic Table. The electronic configuration of chlorine is 1s2 2s2 2p6 3s2 3p5. As per this electronic configuration, a Cl-atom has a total of 7 valence electrons; it is thus short of one valence electron only that is required so that the chlorine atom can achieve a complete octet electronic configuration.
Conversely, fluorine (F) is also present in Group 17 of the Periodic Table. The electronic configuration of a fluorine atom is 1s2 2s2 2p5. According to this electronic configuration, an F-atom has a total of 7 electrons in its valence shell. Thus, again it lacks one more electron to complete its octet electronic configuration.
The ClF5 Lewis dot structure displays a total of five Cl-F bonds. 5 valence electrons of the central Cl-atom used in covalent bonding out of the 7 initially available leaves behind 2 valence electrons i.e., 1 lone pair on the central Cl-atom.
However, each F-atom contains 3 lone pairs. In this way, all the bonded atoms attain a completely stable octet electronic configuration via lone pairs and chemical bonding in ClF5.
Due to the presence of one lone pair of electrons on the central Cl-atom in ClF5, there is a distortion witnessed in the asymmetrical square pyramidal shape and geometry of the molecule.
Atom
Electronic configuration
Valence electrons
Fluorine (9F)
1s2 2s2 2p5
7
Chlorine (17Cl)
1s2 2s2 2p6 3s2 3p5
7
The electronegativity difference in ClF5 between Cl-atom (E. N= 3.16) and F-atom (E. N= 3.98) in each of the five Cl-F bonds is 0.82 units.
Hence, the fluorine atom with higher electronegativity gains a partial negative (Fδ-) charge while the central chlorine atom obtains a partial positive (Clδ+) charge (as shown below).
As a result, in ClF5, all Cl-F bonds are individually polar with an electronegativity difference of 0.82 units.
Dipole Moment
Dipole moment (μ) is a vector quantity that points from the positive pole to the negative pole of a bond or a molecule.
It is mathematically calculated as a product of the magnitude of charge (Q) and charges separation (r). The dipole moment is expressed in a unit called Debye (D).
The dipole moment of a polar covalent bond conventionally points from the positive center to the center of the negative charge.
So in polar bonds of ClF5, the dipole moment of each Cl-F bond points from Clδ+ to Fδ-(as shown below).
Molecular geometry
According to the valence shell electron pair repulsion (VSEPR) theory of chemical bonding, ClF5 is an AX5E1-type molecule. To one Cl-atom at the center (A), five bonded atoms (X) are attached (five F-atoms) and the central Cl-atom contains one lone pair (E).
Lone pair-bond pair repulsions are present in the molecule in addition to bond pair-bond pair repulsions. Therefore, the molecular geometry or shape of ClF5 is square pyramidal which is different from its ideal electron pair geometry i.e., octahedral.
To minimize the electronic repulsions and to attain stability in a square pyramidal structure, the bonded atoms in the ClF5 molecule possess a mutual bond angle of (∠F-Cl-F) 90°.
Due to the presence of one lone pair of electrons on the central Cl-atom, the ClF5 molecule has square pyramidal molecular geometry. Highly electronegative F-atom strongly attracts the shared cloud of the Cl-F bonds on each side of the molecule. Hence, the Cl-F bonds are individually polar.
The Cl-F dipole moments do not get canceled uniformly on each side of the molecule due to asymmetrical shape. This leads to a charged electron cloud spread over the molecule.
Consequently, pentafluoro chlorine (ClF5) is overall a polar molecule (net µ = 1.8 Debye).
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), bromine trifluoride (BrF3), phosphorus trifluoride (PF3), chlorine pentafluoride (ClF5), etc.
Examples include oxygen (O2), nitrogen (N2), methane (CH4), carbon disulfide (CS2), ethane (C2H6), propane (C3H8), etc.
ClF5 has five Cl-F bonds and an asymmetrical square pyramidal molecular geometry.
The electronegativity difference between the bonded Cl-atom (E. N= 3.16) and F-atom (E. N= 3.98) is 0.82 units. Therefore, bonded atoms gain partial positive (Clδ+) and partial negative (Fδ-) charges. Hence, each Cl-F bond possesses a particular dipole moment
Due to the presence of one lone pair of electrons on the central Cl-atom, overall molecular geometry is asymmetrical, and the electron cloud is not uniformly distributed.
Consequently, the dipole moment does not get canceled, and overall ClF5 molecule is polar withnet µ = 1.8 Debye.
Is BrF5 more polar than ClF5?
BrF5 consists of five Br-F bonds. The electronegativity difference in BrF5 is 1.02 units between the bonded Br-atom (E. N= 2.96) and F-atom (E. N= 3.98).
On the other hand, ClF5 contains five Cl-F bonds. The electronegativity difference in ClF5 is 0.82 units between the bonded Cl-atom (E. N= 3.16) and F-atom (E. N= 3.98).
Hence, due to the relatively higher electronegativity difference, the polarity of the Br-F bond is greater than that of the Cl-F bond.
Both BrF5 and ClF5 are polar molecules with an identical, asymmetrical square pyramidal shape. However, BrF5 is more polar than ClF5 due to a higher bond polarity.
Why is SF6 non-polar while ClF5 is a polar molecule?
In sulfur hexafluoride (SF6), there are six polar S-F bonds having an electronegativity difference of 1.4 units between the bonded atoms.
All atoms in the ClF5 molecule including chlorine and fluorine obtain a formal charge equal to zero.
Hence, there are no or zero overall charges present on the chlorine pentafluoride molecule.
Summary
Chlorine pentafluoride (ClF5) is a polar molecule.
It consists of five Cl-F bonds.
Cl-F bonds are polar with an electronegativity difference of 0.82 units between the bonded Cl-atom (E.N = 3.16) and F-atom (E. N= 3.98).
ClF5 has a square pyramidal molecular geometry and shape with a bond angle of (∠F-Cl-F) 90°.
Due to the presence of one lone pair of electrons on the central Cl-atom, the ClF5 molecule has an asymmetrical square pyramidal molecular shape.
The individual dipole moments of polar Cl-F bonds do not get canceled due to the asymmetrical shape.The net dipole in ClF5 is µ =1.8 D; hence Pentafluoro chlorine is overall a polar molecule.
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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