Arsenic atom

The arsenic atom also imparts toxic properties to a higher degree than the sulphur atom. It is a general rule that substances containing a trivalent arsenic atom have a considerably greater 

The arsenical war gases contain halogen atoms or organic radicles such as —CN, —SCN, etc., besides the arsenic atom. The nature of the aggressive action depends on the number and the nature of the organic radicles with which the arsenic atom is linked. 

In general, arsenical compounds have an aggressive action when two of the three valences of the arsenic atom are linked to like atoms or groups and the third to a different atom or radicle. If all the three valences of the arsenic atom are linked to similar atoms or radicles the compound has practically no aggressive action. Thus in the series of chlorovinyl arsines, it has been found that trichlorovinyl arsine has practically no aggressive action compared with chlorovinylchloroarsine or dichlorovinyl chloroarsine  

In the series of aromatic arsines there is a great difference in aggressive action between triphenyl arsine, phenyl dichloroarsine and diphenyl chloroarsine. 

The presence of halogen atoms in the molecules of organic arsenicals usually confers irritant properties. Among these halogen compounds, those containing chlorine have a superior irritant power to the analogous bromine and iodine compounds, e.g., diphenyl chloroarsine has a greater irritant power than diphenyl iodoarsine. 

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For a reconstmcted surface, the effect of an adsorbate can be to provide a more bulk-like enviromnent for the outemiost layer of substrate atoms, thereby lifting the reconstmction. An example of this is As adsorbed onto Si(l 11)-(7 X 7) [37]. Arsenic atoms have one less valence electron than Si. Thus, if an As atom were to replace each outemiost Si atom in the bulk-temiinated stmcture, a smooth surface with no impaired electrons would be produced, with a second layer consisting of Si atoms in their bulk positions. Arsenic adsorption has, in fact, been found to remove the reconstmction and fomi a Si(l 11)-(1 x l)-As stmcture. This surface has a particularly high stability due to the absence of dangling bonds. 

Cyclic and Polymeric Substances Containing Arsenic—Arsenic Bonds. A number of organoarsenic compounds containing rings of four, five, or six arsenic atoms have been prepared (cycHc polyarsines). The first such four-membered ring compound to be adequately characterized, tetrakis (trifluoromethyl) tetrarsetane [7547-15-17, was obtained by the interaction of a diiodoarsine and mercury (107,108) ... 

The dodecahedral coordination is produced by two interpenetrating tetrahe-dra (slightly distorted) of chlorine and arsenic atoms. 

Self-Test 1.12B Write the ground-state configuration of an arsenic atom. 

Pig. 1. Diagram showing the forward half of the unit cube of binnite. Large circles represent sulfur atoms, small open circles copper atoms, and small shaded circles arsenic atoms. Bonds between adjacent atoms are indicated. Note that there are two kinds of copper atoms and two kinds of sulfur atoms. 

Semiconductor properties are imparted by doping its structure with boron, phosphorus, or arsenic atoms. Silicon is relatively inert chemically but is attacked by halogens and dilute alkalies. It has good optical transmission especially in the infra-red. 

The study of the radiochemical reactions of arsenic atoms in benzene solution was carried further by comparing the product spectra of neutron irradiated ASCI3 solutions and GeC solutions which have undergone beta decay. The product spectra were found to be remarkably similar, especially when considered only as to the number of As-0... 

It is noteworthy that photoluminescent poly(vinylene-arsine)s have also been prepared by radical copolymerisation of phenylacetylene and an arsenic atomic biradical equivalent [71]. 

As well as sulfur, macrocycles containing other large donors such as tertiary phosphorus or arsenic atoms are also known, although the metal-ion chemistry of such ligands has been somewhat less explored. In part, this reflects the synthetic difficulties often encountered in the preparation of ligands containing these heteroatoms structures (49) (Horner, Walach Kunz, 1978), (50) (Kauffmann Ennen, 1981), and (51) (Mealli etal., 1985) provide three representative examples of such macrocycles. 

In ultra pure crystalline silicon, there are no extra electrons in the lattice that can conduct an electric current. If however, the silicon becomes contaminated with arsenic atoms, then there will be one additional electron added to the silicon crystal lattice for each arsenic atom that is introduced. Upon heating, some of those "extra electrons will be promoted into the conduction band of the solid. The electrons that end up in the conduction band are able to move freely through the structure. In other words, the arsenic atoms increase the conductivity of the solid by providing additional electrons that can carry a current when they are promoted into the conduction band by thermal excitation. Thus, by virtue of having extra electrons in the lattice, silicon contaminated with arsenic will exhibit greater electrical conductance than pure silicon at elevated temperatures. 

Arsenic and nitrogen compete for the electrons participating in the natural electron-relay cycles in the body. The number of electrons transferred by nitrogen depends on the number of arsenic atoms competing for them. 

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