Zn element me9/16/2023 The pnictogenides Zn 3N 2 (notable for its high melting point ), Zn 3P 2, Zn 3As 2 and Zn 3Sb 2, have various applications. Of the four zinc halides, ZnF 2 has the most ionic character, whereas the others, ZnCl 2, ZnBr 2, and ZnI 2, have relatively low melting points and are considered to have more covalent character. The other chalcogenides, ZnSe and ZnTe, have applications in electronics and optics. A useful property of ZnS is its phosphorescence. Both Zn and S are tetrahedrally coordinated by the other ion. Zinc sulfide, ZnS, crystallizes in two closely related structures, the zincblende crystal structure and the Wurtzite crystal structure, which are common structures of compounds with the formula MA. Zinc hydroxide, Zn(OH) 2 is also amphoteric. It is amphoteric, dissolving in acids to give the aqueous Zn 2+ ion and in alkali to give the zincate (a.k.a. It crystallizes with the Wurtzite structure. Zinc oxide, ZnO, is the most important manufactured compound of zinc, with a wide variety of uses. With oxidants such as chalcogens and halogens, Zn forms binary compounds such as ZnS and ZnCl 2. When this layer is corroded by acids such as hydrochloric acid and sulfuric acid, the reaction proceeds with the evolution of hydrogen gas. The reaction of zinc with water is slowed by this passive layer. The composition of this layer can be complex, but one constituent is probably basic zinc carbonate, Zn 5(OH) 6CO 3. Pure zinc tarnishes rapidly in air, rapidly forming a passive layer. Zinc is a strong reducing agent with a standard redox potential of −0.76 V. Compounds containing zinc are typically diamagnetic, except in cases where the ligand is a radical. Zinc oxide turns yellow when heated due to the loss of some oxygen atoms and formation of a defect structure. However, zinc selenide and zinc telluride are both coloured due to charge-transfer processes. Exceptions occur when the compound contains a coloured anion or ligand. Zinc compounds, like those of main group elements, are mostly colourless. Calculations indicate that a zinc compound with the oxidation state of +4 is unlikely to exist. No compounds of zinc in oxidation states other than +1 or +2 are known. In this respect zinc is similar to magnesium where low-valent compounds containing a Mg - Mg bond have been characterised. The compounds have the formula RZn 2R and they contain a Zn - Zn bond analogous to the metal-metal bond in mercury(I) ion, Hg 2 2+. Zn(I)Ĭompounds with zinc in the oxidation state +1 are extremely rare. For this reason, zinc ions are at the catalytic centers in many enzymes. the Zn-ligand bonds exchange with other ligands rapidly. Zn(II) complexes are kinetically labile, i.e. Whilst calcium is somewhat larger than magnesium, there is a steady decrease in size as atomic number increases from calcium to zinc. That two elements so different in atomic number have the same radius is a consequence of the d-block contraction. This parallel results from the fact that Zn 2+ and Mg 2+ have almost identical ionic radii as well as filled electron shells. Many zinc(II) salts are isomorphous (have the same type of crystal structure) with the corresponding salts of magnesium(II). Five- and seven-coordination numbers can be imposed by special organic ligands. Six-coordinate octahedral complexes are also common, such as the ion 2+, which is present when a zinc salts are dissolved in water. Tetrahedrally coordinated zinc is found in metallo-enzymes such as carbonic anhydrase. Many complexes, such as ZnCl 4 2−, are tetrahedral. As such, its complexes tend to be symmetrical, ZnO and zinc sulfide, ZnS, (zincblende) in which the oxide and sulfide ions are tetrahedrally bound to four zinc ions. In its compounds, Zn 2+ ions have an electronic configuration 3d 10.
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