[antimatter101]

I just came across the molecule xenon tetrafluoride and found it weird. Xenon is a noble gas, with a stable shell so it is unreactive, but it still forms compounds. I also looked at the pauling electronegativity scale. There was no electronegativity for helium, neon and argon because they didn't form compounds so the electronegativity cannot be measured, but there were units for krypton, xenon and radon. Can someone help me?

[Schrödinger]

Fluorides of Xenon have been reported. http://en.wikipedia.org/wiki/Xenon_fluoride. They certainly are inert gases, but when a very strong oxidizing agent like fluorine is used under harsh conditions, it gets oxidized.

Pauling electronegativity is calculated using the bond enthalpies of the certain coumpounds. (see : http://en.wikipedia.org/wiki/Electronegativity, read under Pauling electronegativity). Since compounds of Xe , etc are known, people probably calculated electronegativities from data pertaining to them like bond dissociation, etc.

[SapereAude1490]

When people were making O₂PtF₆ from PtF₆ and O₂, they found out(using X-rays) that the compound O₂PtF₆ was made up of O₂⁺ ions and PtF₆^- ions.

The ionization energy of O₂ is 12,2eV and of Xe 12,1eV so they tried Xe instead of O₂. When they tried mixing dark red PtF₆ vapors with excess Xe at room temperature, a solid yellow Xe⁺PtF₆^- was formed.

Also, Xenon's outer shell is 5s²5p⁶. The energy difference between these higher quantum states orbitals is small, so you can take a few of these electrons and place them in 5d-orbitals, like this


5s     5p       5d
       

or

       

[EpicWinston]

I was thinking the same thing while taking general chem. It is important to realize this does not happen naturally. The conditions must be harsh, extremly harsh. Another thing to take into perspective is periodic trends. F is extremly elctronegative, Xe is kinda big (electrons are further apart, so they are not as attracted to the nucleus), so if an inert gas was going to react (Under harsh conditions) with any other element wuldn't these two be a good match? 

[antimatter101]

Thanks! SpareAareDUDE you rock! I gave you an extra mole snack!

[antimatter101]

Wait a minute, what is the structure of O2PtF6?

[SapereAude1490]

I have no idea... (goes off to Google it)

Found this http://jcp.aip.org/resource/1/jcpsa6/v44/i5/p1748_s1?isAuthorized=no

Apparently, you can't use electron diffraction to figure out the structure ... strange. I thought you use neutron diffraction to see small molecules like Hydrogen. I guess I have a lot more to learn... 

They also say "The PtF₆^- ion is a regular octahedron with a Pt☒F bond length of 1.82±0.03 Å."

So it's like http://upload.wikimedia.org/wikipedia/commons/0/07/Octahedron.svg, with the Pt atom inside it.

The O₂⁺ bond to PtF₆^- is ionic. Same thing with Xe⁺. That F really can't get enough of electrons. What a selfish prick of an element...

As EpicWinston said, F is extremly electronegative. So if it can take an electron from O₂, it can take it from Xe too.

Also I forgot to say that in Xe


5s     5p       5d
         
        
and

        
           

The first one makes two covalent bonds and the second one four.

In Xe⁺ it's probably the first case where you have two unpaired electrons and one electron is being pulled away more than usual by fluorine, making a cation. The other one is covalent? Don't have a clue really. Maybe it just stays in the Xe p-orbital, making the whole thing paramagnetic, or not. I'll see what I can find.

[antimatter101]

Thanks! Another mole snack... tomorrow.

What about gratitude?

[SapereAude1490]

Yeah, yeah.