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Author: Subject: Allotropes
chemkid
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[*] posted on 18-12-2007 at 14:29
Allotropes


After melting sulfur today, i looked up some of the different allotropes of sulfur. Being my search, the endeavour quickly turned into a search for allotropes for all allotropes of the non radioactive elements. (i just don't like radioactive elements) So here is what i have got so far. Its not much. I found some interesting ones UTFSEing. I hope you can help....or improve sulfur. Apparently there are a ton of allotropes, but i can't find anything actually listing them. (all the books i found blocked many of the important pages)

Hydrogen
Helium
Lithium
Beryllium
Boron
Carbon: Graphite, Diamond, Buckyballs, Nanotubes, Lonsdaleite, Chaoite, Schwarzite, Filamentous Carbon, Carbon Aerogels, Amorphous
Nitrogen:
Oxygen: dioxygen (O2), ozone (O3), tetraoxygen (O4), Metallic oxygen?
Fluorine
Neon
Sodium
Magnesium (no allotropes)
Aluminum (no allotropes)
Silicon
Phosphorus: White (P4), Red, Black
Sulfur: Monoclinic, Amorphous (flowers of sulfur), Rhombic (over twenty)
Chlorine
Argon
Potassium
Calcium
Scandium
Titanium (no allotropes)
Vanadium
Chromium
Manganese (4 Allotropes)
Iron alpha, beta, gamma
Cobalt
Nickel
Copper
Zinc
Gallium
Germanium
Arsenic Gray gamma arsenic, yellow alpha arsenic, Black amorphous arsenic
Selenium black, amorphous, red
Bromine
Krypton
Rubidium
Strontium
Yttrium
Zirconium
Niobium
Molybdenum
Technetium
Ruthenium
Rhenium
Palladium
Silver
Cadmium
Indium
Tin: White, Gray
Antimony
Tellurium
Iodine
Xenon
Cesium
Barium
Lanthanum
Cerium
Praseodymium
Neodymium
Promethium
Samarium
Europium
Gadolinium
Terbium
Dysprosium
Holmium
Europium
Gadolinium
Terbium
Dysprosium
Holmium
Erbium
Thulium
Ytterbium
Lutetium
Hafnium
Tantalum
Tungsten
Osmium
Iridium
Platinum
Gold
Mercury
Lead
Bismuth

Thankyou woelen
Thankyou -Jeff B
[Edited on 18-12-2007 by chemkid]

[Edited on 18-12-2007 by chemkid]

[Edited on 19-12-2007 by chemkid]

[Edited on 19-12-2007 by chemkid]

[Edited on 19-12-2007 by chemkid]




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woelen
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[*] posted on 18-12-2007 at 14:32


Selenium also has multiple allotropes, there is black selenium, amorphous selenium and red selenium.

[Edited on 18-12-07 by woelen]




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[*] posted on 18-12-2007 at 18:50


Alpha, gamma, delta iron.

Wikipedia claims that plutonium has seven allotropes, with densities varying over a ratio of 4:3.

I see an offhand mention in a patent that aluminum, magnesium and titanium are non-allotropic. This article appears to claim otherwise for titanium.

The term "allotropy" itself seems to take a number of distinctive forms. It can refer to:

* elemental states with different molecular compositions (oxygen and ozone)

* metallic states with different crystal structures (iron allotropes)

* different crystal structures of a compound (ice Ih and Ic through XII, plus amorphous ice)

* conventional and superfluid forms of helium

* different spin states of molecular hydrogen (ortho- and para-hydrogen)

I never knew the term was that broad...
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[*] posted on 18-12-2007 at 19:32


Here is a thread that I started in a similar vein though not trying to be so comprehensive.

https://www.sciencemadness.org/talk/viewthread.php?tid=2226

Really most of the allotropes of the metals are just plain boring, slight changes in density abound, so it certainly limits the number of allotropes that I find interesting, mostly to the non-metals though there are some interesting ones in the metallic kingdom such as the aforementioned tin and for some reason plutonium.

I also posted on the somewhat extensive ability of phosphorus to change itself in the following thread:

https://sciencemadness.org/talk/viewthread.php?tid=3563

[Edited on 12/18/2007 by BromicAcid]




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chemkid
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[*] posted on 19-12-2007 at 12:12


@-jeffB You raise a lot of good questions.

If anyone can pin down exactly what an allotrope is or if it is it very general term?

@Bromic Acid i saw the thread which is were i got much of my information from that was originally on the list. :P

At this point i think i am going to stick to different crystal structures. Correct me if this renders the list now wrong.

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[*] posted on 19-12-2007 at 15:13


I think you should narrow your research and listing to the separate allotropes that are relatively stable at room temperature. Many many metals have alpha-beta-gamma crystal modifications at unreasonable temperatures and pressures.

For example, in my element collection, I have amorphous (brown) and crystalline boron, red violet white and black phosphorus, graphite, glassy carbon, fullerenes, pyrolytic graphite, highly ordered pyrolytic graphite, diamond, nanosoot, red and black selenium...etc. I've been looking into the allotropes of arsenic, but these seem just too unstable at room temperature.




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[*] posted on 19-12-2007 at 16:22


that sounds good. I think i'lll limit to allotorpes that are stable at standard temp and pressure for at least 24 hours.

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