XeF4 is the first discovered binary compound of a noble gas.When xenon (Xe) undergoes a chemical reaction with fluorine (F2), XeF4 is produced.It's chemical or also called IUPAC name is Xenon tetrafluoride.
Xe +2 F2→XeF4
This reaction produces a high amount of heat at the time offormation and so it has been categorized as an exothermic reaction where nearabout 251KJ/mol energy releases per reaction.
Xenon tetrafluoride is a white crystalline solid in appearancehas density 4.040 g/cm3, molar mass 207.283 g/mol, and melting point 117°C.
It is soluble in water and hydrolyses at low temperature toform different compounds like xenon, oxygen, xenon trioxide (XeO3), and hydrofluoric acid (HF).
In this article, we are going to know about the polarity of XeF4 meanswhether it is a polar or nonpolar molecule in full detail. But before that, letshave some ideas about what polar and nonpolar molecules are:
Polar Molecules
Polar molecules are those molecules that have a net dipolemoment and this is possible only if there is an electronegativity differencebetween the associated atoms as well as asymmetrical geometry so that the induceddipole charges do not cancel each other.
There are somecertain conditions for the molecule to be polar i.e. have asymmetrical structure,presence of lone pair of electrons or electronegativity difference betweencentral atom to bonded atoms.
Polar molecules have polar covalent bonds or ionic bonds.They are soluble in water (called hydrophilic) and other polar solvents like hydrochloric acid(HCl), ammonia (NH3), Nitrogen dioxide (NO2)sulfur dioxide (SO2), etc.
Nonpolar Molecules
Nonpolar molecules are considered as pure covalent bond becauseit forms by equal sharing of electrons between the atoms in a compound and thisis what covalent bond is known for.
One more case for the nonpolar molecule if the moleculeshave symmetrical structure so that the induced partial charges on the individualatoms nullify each other and the net dipole moment becomes zero.
As these are a pure covalent bond so they are insoluble inwater (called hydrophobic) and other polar solvents but are soluble in nonpolarsolvents like carbon tetrachloride (CCl4), carbon dioxide (CO2), benzene (C6H6)etc.
Now, Is XeF4 polar or nonpolar? XeF4 is a nonpolarmolecule despite four individual Xe-F bonds are polar. This isbecause XeF4 has an octahedral symmetric geometry. The polarity induced on four Xe-F bonds are cancel each other and the net dipole moment becomes zero.
Why is XeF4 a nonpolar molecule? [Detailed Explanation]
As we have already known there are certain conditions for amolecule to be polar or nonpolar in the above definitions of a polar molecule andnonpolar molecule. The same things apply here which makes XeF4 a molecule.
In XeF4, there are four fluorine atoms are bonded with a central xenon atom. Also, there are two lone pair of nonbonding electrons arelocalized on the central Xe atom.
The Xe-F bonds are polar as the electronegativity differencebetween xenon (2.6) and fluorine (4.0) is 1.4. But we know molecular polarityis a vector quantity which means net polarity is the vector sum of individualbond dipoles.
According to the VSEPR theory, MX4E2 structured haveoctagonal electronic geometry which makes XeF4 molecular geometry square planari.e. the angle between F-Xe-F is 90°(Symmetrical).
The molecule is symmetrical so that all the Xe-F bonddipoles are opposing each other, as a result, the net dipole charge becomes zero.
But as shown in the above diagram, there are still two pairs ofnon-bonding electrons that are presence on the central Xe atom which are aligned at 180°so that their effects are also nullified. And there is not any dipole chargepresence on the molecule which makes XeF4 a nonpolar molecule.
Check Out: Is XeF2 Polar or Nonpolar?
XeF4 Polar or Nonpolar (Based on polarity determiningfactors)
These are some of the major factors which are used to determine the polarity of the compounds:
Electronegativity difference
Electronegativity is a kind of force exerted by atoms on theirbonding partners at the time of bond formation. All the atoms have their ownelectronegativity value which varies from atom to atom. Some have higher EN value andsome have lower EN value.
The atoms having higher electronegativity value attract theelectrons pair from the bonding partners. It means higher the electronegativitydifference between atoms, the more uneven sharing of electrons takes place. In theperiodic table, the fluorine (F) atom has the highest electronegativity value of 4.0, andfrancium (Fr) has the lowest 0.7.
In the XeF4 compound, the electronegativity difference between fluorine(4.0) and Xe (2.6) is 4.0-2.6= 1.4 which shows the Xe-F bond is polar according tothe Pauli scale.
Molecular geometry
The central atom of XeF4 (Xe) has a total of 12 electronslocalized in the form of 8 as Xe-F bonding and 4 as non-bonding pairs. So, wehave an MX4E2 structure which is according to VSEPR theory, an octahedralelectronic geometry means XeF4 has square planar molecular geometry.
And due to the symmetrical structure, the polarity of the Xe-F bond cancel each other and no dipole charge induced on the molecule.
Dipole moment
The dipole moment is defined as the products of induced chargeand distance of separation between the atoms. It is given as,
Dipole moment = Charge (Q) * distance of separation (d)
Its unit is Debye and denoted by ‘D’. 1D = 3.33564*10-30 C.m,where C is Coulomb and m is meter.
The dipole moment is the major aspect for any compound to bepolar or nonpolar. All the polar molecules have a net dipole moment and allnonpolar have zero dipole moment.
XeF4 is a nonpolar molecule so that its dipole moment is 0D(Zero).
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