The Noble Gasses

[COMMUNIST FLISK]

so this thread is just to ask questions about some useful (yet slightly boring chemicals) namely, the noble gasses.

my question. we can ionise the noble gasses easily (mass spectrometer etc) for instance: Ar+, Ar 2+ etc. If a negative chloride ion (Cl-) was introduced to a sample of ionised argon, why would they not react to form ArCl?

 

[Lichtbringer]

Because of enrergy. Since the energy sum of Ar+ + Cl- is less stable than Ar + Cl* (Chlronie radical), they react to form the latter. They could form a van-der-waals molecule afterwards. But I don't deem that likely, since the energy output from the previous reaction should easily be high enough to cause the molecules to dissociate.

 

[yarps]

There are a few compounds involving noble gases, though. IIRC, all of them except Helium have been observed to bond with something. See also http://en.wikipedia.org/wiki/Noble_gas_compound .

 

[Lichtbringer]

That depends on how you define a bond or a compound. Helium forms molecules by very weak van-der-waals interaction. I would call that a compound. The layers of graphite are only bound by vdW forces and noone would call graphite a 2-dimensional compund.

 

[COMMUNIST FLISK]

helium is not a compound as a compound is defined as a molecule containing more than one element.

 

[Lichtbringer]

Correct, but helium forms van-der-Waals molecules with other noble gases. They are quite unstable but they exist, I once did an experiment on them via microwave spectroscopy.

Graphite is a compound, since the edges of it's layers are saturated by hydrogen. It is a pure element in quite good approximation, but im reality it's still a compound.


PS: I don't want to pull ranks here, but I have a diploma in chemistry and know how a compound is defined. Thank you very much.

 

[COMMUNIST FLISK]

the van-der-waals forces of the noble gasses are very weak

and ok then smarty-pants =P

i thought graphite was layers of carbon with partially delocalised electrons filling the gaps

 

[yarps]

That depends on how you define a bond or a compound. Helium forms molecules by very weak van-der-waals interaction. I would call that a compound. The layers of graphite are only bound by vdW forces and noone would call graphite a 2-dimensional compund.

Well, I did say IIRC; I haven't studied chemistry for 10 years. And I certainly don't want to claim that I know how terminology is used among professional chemists. Still, I've never thought of things bound by van der Waals interactions as compounds.

On which note, when you say

Correct, but helium forms van-der-Waals molecules with other noble gases. They are quite unstable but they exist, I once did an experiment on them via microwave spectroscopy.

just how unstable do you mean? How long do they live?