Introduction
Sir William Ramsay received the Nobel prize in 1904 in Chemistry for discovering “Noble Gasses”. These are also called inert gasses as they do not react easily or react rarely. Xenon is one of the inert gasses and due to its stable electronic configuration, it rarely forms compounds with other elements. Although if we compare it with other inert gasses, due to its large size it is more reactive than those and forms bonds with other elements.
Xenon difluoride is a compound of xenon and fluorine. It is a powerful fluorinating agent composed of one xenon atom and two fluorine atoms. It is one of the most stable xenon compounds. It is a dense white crystalline solid. It is believed that it was probably 1st created by German Chemist Rudolf Hoppe in early 1962. He created it by mixing fluorine and xenon in an electrical discharge. Although the 1st published report of xenon difluoride came in October 1962 by Chernick, et al.
Xenon is a Noble Gas, but It Forms the XeF2 Compound, Why?
You must be having this question in mind as xenon is an inert gas and inert gasses don’t react. Yeah, xenon is an inert gas and has a stable electronic configuration with filled outermost orbitals. But its inner electrons screen the outer electrons from the nucleus as xenon is a large size element. So, its outermost electrons experience a weaker attraction force to the nucleus.
Highly electronegative and small-sized elements target the outermost electrons of xenon. Hence, valence electrons of xenon get attracted by fluorine and they get bonded.
Bonding in XeF2
It was earlier believed that noble gasses could not react at all but the production of the first true chemical compound with xenon immediately raised lots of questions. This compound was XePtF6 and it made people wonder whether the previous models of bonding were still valid. After due research was carried out, it became clear that the same models can be applied both for interhalogen and halogen oxy species. Two methods of bonding were explained. These were:
The molecular orbital model and
The valence shell electron pair repulsion scheme.
Structure of Xenon Difluoride
To understand the structure of xenon difluoride you need to know the electronic configuration of xenon and fluorine. Electronic configuration of xenon – Kr 4d10 5s2 5p6 Outermost electrons at Ground State (Xe) –
At excited state (Xe) – Electronic configuration of fluorine – He 2s2 2p5F–
At excited state, xenon has two unpaired electrons while fluorine has one unpaired electron and needs one electron to get a stable electronic configuration like neon. So, two fluorine atoms get bonded with one xenon atom covalently.
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Xenon Difluoride (XeF2)Xenon has 8 valence electrons. Out of which 2 electrons form sigma bonds with fluorine atoms while the remaining 6 electrons remain as 3 lone pairs. It shows hybridization sp3d as at excited state of xenon you can see ones, 3 -p and one d orbitals are taking place in hybridization. You can also calculate its hybridization by the number of sigma bonds and lone pairs in xenon.
As in sp3d hybridization, two hybridizations are involved – sp2 and PD. Sp2 forms equatorial bonds while PD forms axial bonds. Percentage of s- character in sp2 is 33.33% while in PD it is zero. As there is tremendous repulsion between the lone pairs so they get placed at larger bond angles which are possessed by equatorial bonds (120°). So, lone pairs of xenon get placed at equatorial positions i.e. vertices of the triangle. While fluorine atoms get placed at axial position. Thus, the shape of XeF2 is linear and the geometry is trigonal bipyramidal.
Linear Synthesis of Xenon Difluoride
It is synthesized by the reaction of xenon and fluorine gasses in presence of heat, irradiation, or an electrical discharge. Thus, obtained xenon difluoride is solid. It is purified by fractional distillation or selective condensation using a vacuum duct. (Image to be added soon)It can also be synthesized by dioxygen difluoride.
Properties of Xenon Difluoride
XeF2 is soluble in solvents such as BrF5, BrF3, anhydrous hydrogen fluoride, methyl cyanide and IF5. Its molar mass is 169.290 g.mol-1.
It is the most stable xenon compound. It is moisture sensitive. It releases toxic compounds in contact with moisture. It decomposes in contact with light or water vapor.
It is a dense, white coloured crystalline solid. It has a nauseating odor and low vapor pressure. Its melting point is 128.6℃. It is corrosive to exposed tissues. Its shape is linear. It is soluble in water. Solubility in water is 25g/L at 0℃.
The xe-F bond length in solid xenon difluoride is 200 picometre while in vapor state it is 197.73 picometre.
Applications of Xenon Difluoride
Few applications of XeF2 are listed below –
It is used as a strong fluorinating agent.
It works as an oxidizing agent as well.
It is used as an isotropic gaseous etchant for silicon particularly in the production of microelectromechanical systems.
It has a high etch rate and does not require external energy or ion bombardment for the etching of silicon.
It is used to analyze sulfur, selenium and tellurium in the number of compounds.
It is also used for the detection and determination of the amount of iodine.
Its reaction with uracil is used for the production of the anticancer drug 5-fluorouracil.
Caution must be taken while using XeF2 as when it reacts with moisture it produces toxic and explosive substances.
This was all about Xenon difluoride, if you are looking for solutions to NCERT problems related to XeF2, then log on to the Vedantu website or download Vedantu Learning App. By doing so, you will be able to access free PDFs of NCERT Solutions as well as Revision notes, Mock Tests and much more.
FAQs on Xenon Difluoride
1. What are the various noble gasses?
As of today, we know about 118 elements of the periodic table. 94 of these elements occur naturally while the rest have been manufactured synthetically. The seven chemical elements that constitute Group 18 (VIIa) of the periodic table are referred to as noble gasses. These noble gasses are namely helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og). If we talk about the physical properties of these gasses, they are colorless, odorless, tasteless, and nonflammable. Group 18 was earlier called Group 0 because it was believed that noble gasses could not bond with other elements but recent discoveries have proved this statement wrong. The electronic configuration of these elements has now shown that some of them do indeed form compounds. This is why Group 0 was then relabelled as Group 18.
2. Why is XeF2 used as an oxidizing and fluorinating agent?
A lot of research has gone into understanding why XeF2 has considerable potential in oxidative fluorination. Studies have shown that this is mostly because of the compound’s low average bond energy which stands at a measly 133.9 kJ/mol. Moreover, xenon is also a very non-reactive gas and does not react quickly. This is why it is surprising to see that XeF2 has considerable kinetic stability. This implies that this noble gas compound might be recovered from an aqueous solution in which it is thermodynamically unstable towards hydrolysis using several techniques. One such extraction technique is extraction with CCl4 or fractional distillation.
3. What other compounds does xenon form?
Xenon mostly reacts with fluorine and oxygen to form fluorides and oxides. These compounds are listed below:
Xenon Difluoride(XeF2): This compound is prepared by heating Xenon and fluorine in the ratio 2:1 at 400 degrees C and 1 bar pressure. The heating process is carried out in a sealed nickel tube.
Xenon Tetrafluoride (XeF4): This compound is prepared by heating Xe and F2 in the molecular ratio of 1:5 at 400 degrees Celsius and 6 atm. This heating process is also carried out in a sealed nickel tube.
Xenon Hexafluoride (XeF6): This compound is prepared by heating xenon and fluorine in the ratio of 1:20 at 300 degrees Celsius and 60 atm. This heating has to be carried out in a nicked vessel.
Xenon Trioxide (XeO3): This compound is prepared by the slow hydrolysis of xenon hexafluoride (XeF6).
Xenon Tetroxide (XeO4): This compound is prepared by treating barium perxenate with anhydrous sulphuric acid.
4. How can students learn about the other noble gasses?
As we have already mentioned, discoveries have shown that noble gasses can now react with other elements and form compounds. You can learn all about Noble Gasses- Their Names, Properties, Uses, and FAQs by clicking on the link that has been highlighted. This will enable you to get some in-depth knowledge about this topic. Inorganic Chemistry is an important part of the whole Chemistry syllabus of any class and at least 1 or 2 questions are asked from noble gasses in the final examination every time.
5. From where should students study Xenon for their IIT JEE exam?
When it comes to coveted examinations like the IIT JEE, revision is the name of the game. You can study all about Physical and Chemical and Electronic Configuration of Noble Gas for IIT JEE Chemistry from Vedantu’s website in the exam. Additional mentoring is also provided to you by the top teachers of the country. Xenon is one such noble gas that is particularly important from the examination point of view. Go through the textbook, make your notes, and keep revising to pass your exams with flying colors.