Xenon (Xe) is a noble gas element in the periodic table. It is chemically nonreactive in nature. But at high temperature and pressure, it undergoes the reaction. The first compound of the noble gas element was Xenon Tetrafluoride (XeF4). In this post, we discuss “Is XeF4 polar or nonpolar ?”. This is a general question students of chemistry used to ask. Because Fluorine is a high electronegative halogen family element and polarizes the chemical bond.
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The first binary chemical compound of a noble gas element was Xenon Tetrafluoride (XeF4). Because of its symmetrical square planar form, xenon tetrafluoride (XeF4) is a non-polar chemical compound in nature. Since the electronegativity value of the Xe and F atoms is unequal, the individual Xe-F bonds are polar in nature, but the net vector number of the polarities of the Xe-F bonds is zero because they cancel out along four opposite directions. As a result, XeF4 has a net dipole moment of 0 Debye.
The synthesis of XeF4 is the result of a mixing of reactant Xenon (Xe) and Fluorine (F2) gases in a specific ratio at a high temperature and pressure in an enclosed nickel vessel. The structure of this colorless, crystalline substance (XeF4) has been determined using analytical chemistry methods: F-isotope NMR spectroscopy and powder and single X-Ray crystallography.
Table of Contents
Xef4 Molecular Geometry, Lewis Structure and Polarity
Synthesis of XeF4:
Xenon Tetrafluoride (XeF4) are synthesized by mixing of Xenon (Xe) monoatomic and fluorine(F2) gases of 1:5 volume ration at 873 K temperature and 7 bar pressure in an enclosed nickel vessel for 1 to 5 hours.
Xe +2 F2 — High temperature and pressure—> XeF4
Nickel metal does not serve as a catalyst in this reaction. It’s only used because the Ni in the containers interacts with Fluorine in the reaction mixture, forming a defensive protective, and non-peeling coating of NiF2 (Nickel fluoride) on the tube or container’s inner walls.
In colorless solid form, the XeF4 has a density of 4.040 g/cm3 and has a solid white appearance. It appears as a colorless crystalline under normal conditions. It can undergo sublimation.
Molecular Geometry Properties:
|Name of molecule||Xenon Tetrafluoride (XeF4)|
|No of Valence Electrons in the XeF4 molecule||36|
|Hybridization of Xenon Tetrafluoride (XeF4)||sp3d2 hybridization|
|Bond Angles F-Xe-F of XeF4||90 degrees and 180 degrees|
|Molecular Geometry of XeF4 molecule||Square Planar|
To understand its physical and chemical properties of XeF4 molecule, one must first understand its Lewis structure and molecular geometry of XeF4 molecule. Let’s look at Xenon tetrafluoride’s Lewis structure. It follows the octet rule to achieve the Lewis structure.
To build the Lewis structure, we must first determine the valence electrons of Xenon tetrafluoride (XeF4) molecule as well as the atom location in the molecule. In the molecular geometry of the XeF4 molecule, the Xenon(Xe) atom in the center of the square planar geometry, and all four fluorine atoms at the corner of the square planar geometry.
The number of valence electrons in the outermost shell of the XeF4 molecule is 36. Molecular orbital hybridization of XeF4 molecule is sp3d2 hybrid in nature. The bond angle of F-Xe-F of the XeF4 molecule is 90 degrees and 180 degrees. The molecular geometry of the XeF4 molecule is square planar geometry in nature.
The orbitals of the central Xenon atom of XeF4 molecule are hybridised, resulting in the creation of new hybridised molecular orbitals. The 5p orbitals of xenon atom have six electrons and the 5s orbitals have two electrons, in total Xenon atom valence electron is eight. In the ground state of Xenon atom, there are no electrons in d-orbitals or f-orbitals. However, when this atom in XeF4 molecule is excited, two electrons in the p-orbitals move to the d-orbitals in the excited state.
As a consequence of that, there are a total of four unpaired electrons on Xenon atom of XeF4 molecule. Two of the unpaired electrons are in p-orbitals, while the other two are in d-orbitals of XeF4 molecule. In XeF4, these hybridised orbitals trigger sp3d2 hybridization,according to the VSEPR (Valence Shell Electron Pair Repulsion) Theory.
Bond Polarity of Xe-F bond of XeF4 molecule:
Polarity of Xe-F bond of the XeF4 molecule mainly depends on the electronegativity value of Xenon (Xe) and Fluorine(F) atoms. Fluorine (F) atom is more electronegative than Xenon(Xe) atom. The electronegativity value of the Xenon (Xe) atom is 2.6 and that of the fluorine (F) atom is 3.98.
Difference between the electronegative value of Xenon(Xe) atom and Fluorine(F) atom gives some understanding about the polarity of Xe-F bond in XeF4 molecule.
Electronegativity difference of Xe-F in XeF4 molecule = |3.98 – 2.60| = 1.38
This indicates the Xenon(Xe) is having lower electronegativity value than fluorine atom in XeF4 molecule. Electron charge in Xe-F bond in XeF4 molecule is more polarise to fluorine atom as compare to Xenon atom.The difference of electronegativity value of xenon and fluorine are very noticeable. Individual Xenon-Fluorine (Xe-F) bonds in XeF4 molecule are thus polar in nature.
As a result of this property, for a single Xe-F bond in XeF4 molecule, Fluorine will strongly attract electrons towards itself, resulting in a partial positive charge on the Xenon side and a partial negative charge on the Fluorine side.
XeF4 Valence electrons
One atom of Xenon and four atoms of Fluorine make up this Xenon tetraflluoride(XeF4) molecule. To evaluate the total number of valence electrons in XeF4, we can add the valence electrons of both these atoms by using an octet rule.
Valence electrons of Xenon atom in XeF4 = 8
Valence electrons of Fluorine atom in XeF4 molecule = 7*4 ( as there are four Fluorine atoms, we will multiply it by 4)
Total number of valence electrons of Xef4 molecule = 8( electrons from Xenon atom) + 7*4(electrons from fluorine atom)
= 8 + 28
Hence total valence electron of XeF4 molecule is 36. It reflects on the XeF4 lewis structure of the molecule. It will be simpler for us to draw the Lewis structure of Xenon Tetrafluoride (XeF4) now that we know its outermost shell valence electrons from the above calculation. This Lewis dot structure depicts valence electrons surrounding individual atoms xenon and fluorine in a XeF4 molecule, as well as the bond it creates.
The bonds in the system XeF4 are represented by lines between xenon and fluorine atom, while the electrons that are not involved in bond formation are represented by dots in its surrounding. Nonbonding electrons of the XeF4 molecule, also known as lone pairs of electrons on xenon and fluorine atom, are electrons that do not form any bonds in the XeF4 molecule.
We’ll put Xenon in the middle and all the other fluorine atoms around it because it’s the least electronegative value atom in XeF4 molecule. Let’s demonstrate the bonds between each Fluorine and Xenon atom now that we’ve put all of the atoms in XeF4 molecule.
Each bond in the XeF4 molecule takes up two electrons, and since this molecule has four single bonds Xe-F, eight of the 36 valence electrons of XeF4 molecule are used up for the bond formation. Begin to wrap the remaining valence electrons around the atoms of XeF4 molecule. Since one electron was used to form the bond, each fluorine atom would have six valence electrons surrounding it.
we’ve already placed 24 of the 28 electrons around the fluorine atoms of XeF4 molecule. Since Xenon in XeF4 molecule is an exception to the octet rule law, the remaining nonbonding electrons or lone pairs of electrons will be put on it.
Put these two nonbonding electron pairs on Xenon atom of XeF4 molecule, and you’ve got a Lewis structure of XeF4 molecule two lone pairs of electrons on Xenon atom, and six nonbonding electrons on each Fluorine atom.
Is XeF4 polar or nonpolar
XeF4 molecule has a square planar molecular geometry with Xenon atom in the center and fluorine atom in the corner of the square planar. The overall arrangement of the concerned XeF4 molecule is symmetric since the two lone pairs on the Xenon atom are axially opposite each other just above and below the square planar geometry.
The vector number (magnitude and direction both considered) of XeF4 molecule all individual Xe-F bond dipoles determines the XeF4 molecular polarity. There are four Xe-F bonds in the XeF4 molecule, each with its own dipole moment, magnitude, and direction. When the vector number of these dipoles of the XeF4 molecule is computed, the resultant dipole moment is a net-zero Debye.
Around the Xenon atom in the XeF4 molecule, there are five atoms: eight electrons from the four fluorine and xenon bonds (two from each bond) and two electron lone pairs on the xenon atom. Four of these electrons are non-bonding lone pairs on the Xenon atom of the XeF4 molecule.
The diffusion of non-bonding orbitals of xenon atoms is greater than that of bonding orbitals of the XeF4 molecule. As a result, for the least amount of electron-pair repulsion, the localized non-bonding electron pairs on the xenon atom in the XeF4 molecule are located opposite to each other.
The net effective dipole across the entire XeF4 molecule is zero due to the symmetric arrangement of the four Xe-F bonds and two non-bonding electron pairs. As a result, XeF4 molecule is a naturally non-polar molecule. Polarity of Xe-F bond in the XeF4 molecule makes the square planar geometry which cancels each other. Finally, XeF4 molecule is nonpolar in nature.
Factors influencing the Polarity of XeF4 molecule
A number of considerations go into determining whether the XeF4 molecule is polar or non-polar. The dipole moment of XeF4 molecule is used to determine its polarity.
The molecule is said to be polar if the dipole is a significant number (not equal to 0 Debye). Any molecule’s dipole moment, and thus its polarity, is essentially determined by the following factors:
Structure of XeF4:
XeF4 Molecules with a symmetric arrangement of atoms appear to have a vector number of dipole moments that is net-zero. This is because there would be another polar bond with a dipole of equal magnitude and the opposite direction for every polar Xe-F bond of the molecule, resulting in a net addition of zero.
As a result, symmetric XeF4 and BeCl2 molecules are non-polar in nature, while non-symmetric molecules such as SF4 are polar.
Type of bond in XeF4:
XeF4 molecule with Xe-F covalent bond is usually non-polar in nature. This is due to the polarity of Xe-F bond canceled each other the forces in its symmetrical square planar structure, which lead to a zero charge build-up at the XEF4 molecule’s poles.
The presence of a fluorine atom in the XeF4 molecule, on the other hand, results in the accumulation of charges and the polarity of the XeF4 molecule.
Electronegativity value of atoms in XeF4:
Xe-F bond of XeF4 molecule is called non-polar if the fluorine atom that forms it are identical in four corners of square planar geometry or if the difference in electronegativity value of Xenon and fluorine atom in XeF4 molecule, then the difference is less than 0.4.
Check out the article for more information on BeCl2 non-polarity. Any dipole moment of Xenon and fluorine formed in such XeF4 molecule is high and does not contribute to polarity establishment due to it canceled out in all opposite directions.
Charge build-up in XeF4 molecule:
A molecule is said to have polarity when it has an accumulation of negative charges on one end of the molecule and positive charges on the other end of the molecule, as well as a large dipole moment in the molecule.
Because of the lone pairs of electrons between Fluorine and sulfur atoms, SF4 is a polar molecule. The article on the polarity of SF4 can be found here.
on the other hand, information regarding the polarity of the NH3 molecule is from here. More information on Lewis’s structure of H2O is here.
Properties of XeF4 moleculeMolecular weight of XeF4 molecule is 207.29 g/molDensity of XeF4 molecule is 4.10 g/cm3The Vapour pressure of the XeF4 molecule is 3mm at room temperature.Bond angle F-Xe-F of XeF4 molecule are 90° or 180° equitorial and axial position respectively.At room temperature, XeF4 is solid in nature and boiling point of XeF4 molecule is 115.7°CMelting point of XeF4 solid crystal is 116°C.Since it is a compound made up of a noble gas, which is naturally unreactive with other chemicals, the m.p. is higher than non-polar molecules. Its boiling and melting fall in the same point.XeF4 molecule is only slightly soluble in anhydrous HF (hydrogen fluoride) and readily reacts with water (even minute amounts of moisture in the air) to form Xenon Oxide(XeO2).The reaction of XeF4 with water can be depicted by the following chemical equation: 6XeF4 + 12H2O ———-> 2XeO3 + 24HF + 4Xe + 3O2At room temperature, XeF4 appears in the form of colorless crystals.In its pure form, xenon tetrafluoride is stable, but it must be kept free of moisture atmosphere. It can be stored in Nickel or Monel containers forever.
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Applications and Uses of XeF4
XeF4 has very few applications in general. The following are a few of them as listed follows:
The molecule Xenon Tetrafluoride is one of those that is relatively simple to comprehend. Since all of the Fluorine atoms are arranged in a symmetric fashion, the Lewis structure of the XeF4 molecule is one of the simplest. To hold their repulsive forces to a minimum, the lone pairs in the molecule are arranged in an octahedral shape in a perpendicular plane.
In order to summarise this blog post, XeF4 has 36 valence electrons. The central atom of Xenon has two lone pairs of nonbonding electrons. The XeF4 molecular electron geometry is octahedral, and its elemental molecular geometry is square planar. XeF4 is a nonpolar molecule that hybridizes with sp3d2 hybridization.