Elements amphoteric

Elements whose Oxids Unite with Water, Some to Form Bases,. 

Others to Form Acids. Which Form Oxysalts. 

---

Amorphous boron and the amphoteric elements, aluminium and gallium, are attacked by aqueous solutions of sodium hydroxide and... 

In the anion electrochemical series, sulfur, being the less noble element compared to its heavier congeners, occupies an intermediate position between iodine and selenium [(+)F, Cl, Br, I, S, Se, Te(-)]. Selenium, regarded as a metalloid, is a relatively noble element. Tellurium is rather an amphoteric element it can enter into solution in the form of both cations and anions. Regarded as a metal, i.e., with respect to its cations, tellurium occupies a position between copper and mercury. Regarded as a metalloid, i.e., with respect to its anions, it is located on the extreme right of the above series. 

Two tilings about aluminum will interest you as a chemist. One is that aluminum is an "amphoteric element, which means that it can form not only a base (Al(OH)j). hut also an acid (HA 10,). The other is that aluminum sulfate (Al SO, ) has the ability to combine with potassium sulfate (K,SO ) and ammonium sulfate ((NHJjSO,) into beautiful cubic crystals of double salts called alums — KA1 (S04)3 12H,0 and NH4A1(S04),-12H,0. 

Aluminum is an amphoteric element that acts as a nonmetal in alkali and develops a hydrated gelatinous aluminate of a species [Al(OH)4]. As a result of this reaction, certain suspended matter including polysaccharide polyanions coprecipitates by entrainment. This element, applied in atomic or ionic form, is a common technique for commercial isolation of pectin. In acid, Al3+ supposedly neutralizes polyanions to yield the aluminum salt. After precipitation of the pectin-aluminum complex, the metal ligand is removed by acidification and washing. 

ICP-MS dominates the field of environmental assay most metallic and amphoteric elements are susceptible of analysis, and it is often a great convenience (to say nothing of being relatively economical) to be able to assay for all elements of interest in a single analysis. Another feature of ICP-MS, however, has been exploited perhaps even more tellingly than multielement analysis. This is that the sample introduction system lends itself to a wide variety of enhancement schemes, in part because the sample is introduced to the instrument at atmospheric pressure and in part because samples are most often in a water-based (dilute acid) medium. These attributes combine to allow various separation and preconcentration schemes to be implemented on-line or nearly so. 

If no precipitate is obtained, the substance is largely free from heavy metals, and the sodium carbonate treatment may be omitted if more of the solution is required. Certain amphoteric elements may, however, be present in the sodium carbonate solution, e.g. Cu, Sn, Sb, As, Al, Cr, and Mn, dissolved in appreciable quantities manganates, permanganates, and chromates may also be present... 

If a precipitate forms on neutralizing the solution, the presence of arsenic, antimony and tin sulphides and possibly salts of amphoteric elements (lead, tin, aluminium, and zinc) is indicated. The precipitate should be filtered off and rejected, f CaS04 and Ca(B02)2 may separate from sufficiently concentrated solutions. 

Selenium is an amphoteric element whose chemistry and biochemistry has mnch in common with snlfur. The essentiality of selenium in experimental animals was demonstrated in 1957. It was necessary that the animals be vitamin E deficient to manifest selenium deficiency. Selenium manifests antioxidant activity by its incorporation into selenocysteine and its subseqnent participation at the... 

Volatilization is usually utilized for separating individual trace elements from the sample before the determination. The methods based on volatilization are concerned mainly with non-metallic and amphoteric elements which have high vapour pressure in the elemental form (e.g., chlorine, bromine, sulphur), or in compounds with halogen, hydrogen, or oxygen. Other volatilization methods exist for the separation of certain elements, such as the distillation of boron as methyl borate. 

When you studied the Periodic Table, you learned about amphoteric elements, those that would act like a base in some cases and like an acid in others. When a molecule has that ability and is used in an electrophoresis separation, it is called an ampholyte. Ampholytes are used as pH markers and to establish the pH gradient. There are two basic systems, natural and immobilized. 

It should be particularly noted that there are in each horizontal period two alkaline elements, two amphoteric elements and four non-alkaline elements, the first three of the latter giving rise to acids and the fourth being inert. All of the non-metals, incidentally, fall to the right of an oblique line drawn from boron (5) to eka-iodine (85). 

Ammonias, compound, 205 Ammonium, 144 acetate, I4.i bromide. 145 carbonates, 146 chloride, 145 compounds, 144 hydrate. 144 iodide, 145 nitrate, 145 purpnrale, 263 salts of, 145 sulphates, 145 sulphides, 145 sutphydrate, 145 theory, 144 urates, 260 Amorphism, 27 Amphoteric elements, 105 Amygdalin. 829 Amyl nitrate, 199 nitrite. 199... 

Antimony occupies atomic number SI in the periodic table, has an atomic weight of 121.7S, and is one of the amphoteric elements. Metallic antimony has a density of 6.684, a melting point of 630.5 C, and a boiling point of 1380 C. The element is resistant to acids (HF, HCl, HNO3, H2SO4) and to ammonia. It is only dissolved by hot concentrated sulfuric acid and by aqua regia. It is resistant to atmospheric conditions. 

If we consider all the metallic elements, the amphoteric elements, the various possible valence states of many elements, ammonia and the amines, and other organic bases, both monomeric and polymeric, the possible salts that might be discussed are obviously quite extensive. Consequently we will make mention of a somewhat random selection here. 

Aluminium is an amphoteric element occurring in Group III of the periodic table of the elements. Its chemistry in the natural environment is dominated by... 

---