Sciencemadness Discussion Board

Astatine probable vapor colour

ChemistryForever - 13-12-2018 at 15:43

What would be the expected color of an astatine vapor (supposing someone could synthesize it very fast until it decomposes ... )? ( example iodine- violet ).

Abromination - 13-12-2018 at 15:58

Much about Astatine is unknown as it very quickly decomposes. The pure element has never been synthesized and if it was it would be vaporized by the heat of its own radiation. If we could see it, I suspect it would be a dark brown or even black as the color of halogens gets darker as you go down.

Mr. Rogers - 13-12-2018 at 22:03

Quote: Originally posted by ChemistryForever  
What would be the expected color of an astatine vapor (supposing someone could synthesize it very fast until it decomposes ... )? ( example iodine- violet ).


If you go by Iodine and Bromine vapor, it's probably not a logical stretch to say it would be very dark brown. The halogens seem to be very consistent like this.

12thealchemist - 14-12-2018 at 02:21

Would it be possible to calculate the approximate colour by working from the molecular orbitals? These have been calculated, and the colour will come from electronic transitions within a molecule of At2. Being a gas simplifies the problem enormously.

Eddygp - 14-12-2018 at 03:18

Quote: Originally posted by 12thealchemist  
Would it be possible to calculate the approximate colour by working from the molecular orbitals? These have been calculated, and the colour will come from electronic transitions within a molecule of At2. Being a gas simplifies the problem enormously.


Exactly my thoughts. This problem should be exceedingly simple to solve computationally; unfortunately I don't have Gaussian at the moment (back home for Christmas) but an accurate calculation of MOs should give the absorbed colour with a great accuracy.
It's not as if anyone is going to try this empirically... especially in a backyard shed!

unionised - 14-12-2018 at 10:48

I can confidently assert that it is green and yellow in diagonal stripes.
Let me know when anyone actually proves that I'm wrong.

On a related note, does anyone have any software that can predict, from first principles, that iodine vapour (near atmospheric pressure and , say, 100C) is red?

unionised - 14-12-2018 at 10:51

Quote: Originally posted by Mr. Rogers  


If you go by Iodine and Bromine vapor, it's probably not a logical stretch to say it would be very dark brown. The halogens seem to be very consistent like this.

If you look at iodine and bromine vapours it's clear that they are very different- one is brown , one is red.
Hardly "consistent"

DraconicAcid - 14-12-2018 at 10:57

Iodine vapour is brown? It's always looked beautifully purple to me.

Tsjerk - 14-12-2018 at 11:06

Quote: Originally posted by unionised  
I can confidently assert that it is green and yellow in diagonal stripes.
Let me know when anyone actually proves that I'm wrong.

On a related note, does anyone have any software that can predict, from first principles, that iodine vapour (near atmospheric pressure and , say, 100C) is red?


How did you come up with these colors?

I don't know the color of a somewhat pure vapor, but I'm pretty sure the surroundings will be blue colored because of the Cherenkov radiation.

DoctorOfPhilosophy - 14-12-2018 at 11:15

The results of your first principle calculations will depend on whether the vapours are monoatomic or diatomic, which I understand is presently unknown.

12thealchemist - 14-12-2018 at 11:20

To me, bromine vapour is reddish brown, more red than nitrogen dioxide but less red than chromyl chloride vapour. Iodine vapour is unequivocally purple. I would assume that astatine behaves like the rest of the halogens in forming dimers, although the calculation could in theory be run for a monomeric vapour too.

Mr. Rogers - 14-12-2018 at 11:51

Quote: Originally posted by unionised  
Quote: Originally posted by Mr. Rogers  


If you go by Iodine and Bromine vapor, it's probably not a logical stretch to say it would be very dark brown. The halogens seem to be very consistent like this.

If you look at iodine and bromine vapours it's clear that they are very different- one is brown , one is red.
Hardly "consistent"


I don't mean they're the same color - I mean the properties of this group have been very predictable.

12thealchemist - 15-12-2018 at 02:00

There is this diagram on Wikipedia on the Tennessine page:

Valence_atomic_energy_levels_for_Cl,_Br,_I,_At,_and_117.png - 30kB