Science topics: ChemistryMetalloids
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Metalloids - Science topic

A class of nonmetals such as arsenic that have some of the chemical properties of a metal.
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There are several definitions and/or descriptions of metals/metalloids (e.g. Arsenic, Cadmium, & Lead) according to different authors. Authors mostly lend toward different academic backgrounds, for example, chemistry, ecotoxicology, environmental science, health, etc. yet they are discussing in a similar context. But what are the most appropriate terms that define/describe metals/metalloids in the environment and why should we use them uniformly in this context?
1. Heavy metals
2. Potentially toxic metals
3. Potentially toxic elements
4. Toxic metals/elements
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I would say potentially toxic metals.
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Hello everyone. How can we verify from band diagram, weather the band crossing is pointing towards Dirac metals or weyl metals or it is just normal band crossing.? What observation we should make? What confirmations we need to do ? More generally, just looking at the band structure how could we could say. Please guide me. Thanks.
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Arsenic and its species are found highly mobile in environment. Due to the oxidation states in which it occurs makes it significantly reactive with other metals and metalloids compounds. During speciation analysis of environmental samples, difficulties arises when unknow compounds of arsenic are found.
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Dear Muhammad, this is a very interesting and important technical question. There are both natural and man-made sources of arsenic found in the environment. For the number of man-made compounds I do not yet have any reliable information. However, according to the link cited below the Earth's crust comprises more than 320 arsenic-containing natural minerals:
Arsenic in Nature
For more information about the origin of environmental arsenic please also have a look at the following useful link:
Yet another valuable source of information is the following article:
ARSENIC AND ARSENIC COMPOUNDS
Good luck with your work and best wishes, Frank Edelmann
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To understand QM the problem is that sometime there is wrong hypothesis, but as we have learned it from our Professor, it can be very difficult to suspect it. The case of the octet rule is one example. According to this rule in a chemical compound the electrons of the metal complete the shell of the metalloid to give a full outermost shell. But, since 1962 we know that Xenon compounds exist: Chernick C.L., Rec. Chem. Prog., 24, 139-155, (1962), see also “From Ln valence to that of 3d”.
I think that the deep difficulties in QM are in fact to correct our wrong hypothesis.
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One difficulty was to understand the valence of the lanthanum and the other rare earths. It was suppose one 5d electron with La, in strong contradiction with the teaching of the periodic table. With a role of valence of the Xenon shell for the Ln, see “From Ln valence to that of 3d”, this problem disappears.
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Hello every body
Does any one has any idea to help me choose a reasonable basis set for intermediate metal ions (i.e Fe2+, Mn2+, Cu2+ and exc.) interactions with guanine or other DNA organic bases. I will be thank full if you mention the reference article too.
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please take a look at https://www.basissetexchange.org/ here you can select the atoms within the system, after on the left you will see a list of basis sets which you may use for your systems, and at the bottom of the periodic table you will see that you can download the basis set in a Gaussian format if needed.
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Dear all,
Can somebody please put some light on how the position of band inversion, near or away the Fermi level affects the electrical transport and thermal properties in semi-metals?
Thanks in advance!
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Thank you so much for the explanation and the picture, Dear Payal Wadhwa.
I will try to digest the adiabatic continuity hypothesis. Your explanation is very clear, thank you so much.
As I said previously, I am learning. These new materials are no sot intuitive as conventional ones. Your threads in RG are very informative and ask properly many questions regarding fundamental symmetries in solid-state physics.
An excellent review :)
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I know reduction reaction of Silica with carbon, also principle of Zone refining or single-crystal generation process. I also heard of silicon chloride purification process,But I know not ore dressing, beneficiation and pretreatment of silica as well as preliminary purification of silicon (say from 80% Si to 99.9% Si). Please inform me and refer to suitable research
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I studied the extraction of electronic grade silicon from silicon dioxide white sand.
These steps are used:
- The raw materials are white sand from mines with high purity such that one do not need a preparation steps to reduce the cost. In addition to carbon and chip woods.
- Then one extracts a metallurgical grade silicon by running the reduction process an metallurgical electric arc furnace. One gets silicon blocks with purity as low as 98 percent.
- Such silicon is purified by the fractional distillation as in Waker Chemietronics.
where one gets pure compounds of silicon such as SiCl4,....... SiH4.
- Then one uses the so called Siemens process to get pure Si rods.
- Then this rods are crystallized by zone refining or pulling from an ingot Silicon melt.
Best wishes
In order to follow the details of these processes please refer to the book of S MSze, VLSI technology.
I think there is no preparation step for the quartzite.
The most important thing that one selects relatively pure quartzite ore.
Even the purity of the commertial silicon will be worse than tat of the quatrzite ore.
May be there are advanced processes other than this classical process.
Best wishes
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Heavy metals through different mechanisms produces organ specific toxicity. Can any one help in identifying exact mechanism of metal induced toxicity. (metals of importance, Cd, Pb, Hg, Zn, Cu, and metalloids: Arsenic).
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The next paper focused on :The Effects of Heavy Metals on Aquatic Animals and its mechanism , hope it can help
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selenium its metalloid or nonmetal by iupac
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In a recent experimentation where we tested an agent's effect on the oxidative stress status on mice (inflammatory model of IBD), we found that livers and colons present a similar response plot.
In the aim to dig deeper, we tried to test our agent on mitochondrial swelling (in vitro). We were surprised to find that low doses induced a significant decrease in Liver mitochondrial activity compared to colons, which were not affected.
any speculation regarding this phenomena is deeply appreciated.
PS: The agent used has a metalloid characteristics.
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What are the differences between liver and colon mitochondria may be the first question to answer? Some inflammatory products influence some pathways but not others due to their multiple, or single targetted effects.
Logic, not current expertise.
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Currently in study heavy metals (Pb, Cd, Cr) and metalloid (As) in freshwater sediment. just wonder if we can use dry ashing for the digestion instead of wet digestion, eg, using aqua regia
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Since Arsenic compounds are volatiles at high temperatures, its determination can be performed by a non-destructive method, such as X-ray fluorescence analysis (XRF).
Revenko A.G. X-ray fluorescence analysis of rocks, soils and sediments // X-Ray Spectrometry. 2002. V. 31, No. 3. P. 264-273.
T.Yu. Cherkashina, S.I. Shtel'makh, G.V. Pashkova, 2017. Determination of trace elements in calcium rich carbonate rocks by Wavelength Dispersive X-ray Fluorescence Spectrometry for environmental and geological studies. Applied Radiation and Isotopes 130, 153–161. http://dx.doi.org/10.1016/j.apradiso.2017.09.038
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I want to know the mechanism of the reactions of highlighting alkaloids by metals and metalloids
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Please find the journals
• Baiker, A. Chem. Soc. Rev.2015, 44, 7449–7464
• Szöri, K.; Balázsik, K.; Felföldi, K.; Bartók, M. J. Catal.2006,241,149–154
• Augustine, R. L.; Tanielyan, S. K. J. Mol. Catal. A: Chem.1996,112,93–104
• Lavoie, S.; Laliberte, M. A.; Temprano, I.; McBreen, P. H. J. Am. Chem. Soc. 2006, 128, 7588–7593
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What do you think about hydrogen, is it a metal, a metalloid,non metalloid? Why?
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Though hydrogen often placed at the top of the alkali metal column in the periodic table, hydrogen does not, under ordinary conditions, exhibit the properties of an alkali metal. Instead, it forms diatomic H2 molecules, analogous to halogens and non-metals in the second row of the periodic table, such as nitrogen and oxygen. Diatomic hydrogen is a gas that, at atmospheric pressure, liquefies and solidifies only at a very low temperature (20 degrees and 14 degrees above absolute zero, respectively).
Over 70 years ago Wigner and Huntington predicted that if solid molecular hydrogen was compressed to a pressure of 25 GPa it would have a dissociative transition from a molecular solid to an atomic solid with a half-filled conduction band so that it would be metallic. Later, Ashcroft predicted that the putative metallic hydrogen might be a room temperature superconductor. It was also predicted by Ramaker, Kumar, and Harris that high pressure molecular hydrogen would become metallic; a recent publication predicts high temperature superconductivity for the molecular phase. Brovman, Kagan, and Kholas showed that hydrogen would be a metastable metal with a potential barrier of ~1 eV. That is, if the pressure on metallic hydrogen were relaxed, it would remain in the metallic phase, just as diamond is a metastable phase of carbon. Silvera and John stated that Since metallic hydrogen is yet to be produced in the laboratory, none of these ideas have been tested. (Silvera, Isaac F. and John W. Cole. 2010. Metallic hydrogen: The most powerful rocket fuel yet to exist. https://dash.harvard.edu/bitstream/handle/1/9569212/Silvera_Metallic.pdf?sequence=2 )
In 2011 Eremets and Troyan reported observing the liquid metallic state of hydrogen and deuterium at static pressures of (260–300 GPa). In 2015, scientists at the Z Pulsed Power Facility announced the creation of metallic deuterium. On October 5, 2016, Ranga Dias and Isaac F. Silvera of Harvard University released claims of experimental evidence that solid metallic hydrogen had been synthesised in the laboratory. In the preprint version of the paper, Dias and Silvera write: With increasing pressure we observe changes in the sample, going from transparent, to black, to a reflective metal, the latter studied at a pressure of 495 GPa. Prominent members of the high-pressure research community have criticised the claimed results, questioning the claimed pressures or the presence of metallic hydrogen at the pressures claimed.
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Abiotic stresses such as drought (water deficit), excessive watering (water-logging/flooding), extreme temperatures (cold, frost and heat), salinity (sodicity) and mineral (metal and metalloid) toxicity etc. So, which one is your target?
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I propose that in first place we define what is stress. What do you think about? What is your own definiton of stress?
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Values on USA context would be helpful. I have been searching through the USEPA and USDA pages, but looking for more compact values in mg/kg. If US context is not available, global values are also appreciated. 
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Check the work of D. D. MacDonald e.g. "Development and Evaluation of Consensus-Based Sediment Quality Guidelines for Freshwater Ecosystems" available here through ResearchGate
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Schaller, J., Vymazal, J., Brackhage, C., 2013. Retention of resources (metals, metalloids and rare earth elements) by autochthonously/allochthonously dominated wetlands: A review. Ecol. Eng. 53, 106-114.?
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You should look at William Shotyk's (University of Alberta) work on trace metals in the oil sands region of Canada.
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How to bond (leak proof) stainless steel and silicone tube/plastic tube?
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Hi,
I faced the same problem. What I did was to use heat shrinkable polymer tubes of slightly larger diameter than a stainless still tube. I put it with an overlap on a steel tube and used a heat gun. It shrink the plastic tube tightly over the steel one like a glove. Simple, reliable and durable construction. This approach is used in electronics as well.