Hafnium compounds chemical

K. L. Komarek, ed.. Hafnium Physico-Chemical Properties of Its Compounds andEUhys, International Atomic Energy Agency, Vieima, 1981, pp. 11,13,14, 16. Covers tbermocbemical properties, phase diagrams, crystal stmcture, and density data on hafnium, hafnium compounds, and alloys. 

Zirconium and hafnium have very similar chemical properties, exhibit the same valences, and have similar ionic radii, ie, 0.074 mm for, 0.075 mm for (see Hafniumand hafnium compounds). Because of these similarities, their separation was difficult (37—40). Today, the separation of zirconium and hafnium by multistage counter-current Hquid—Hquid extraction is routine (41) (see Extraction, liquid—liquid). 

Hafnium and Hafnium Compounds, 73 Haifa Chemical Co. Ltd., 251 Haifa Chemical Company Ltd., 177 Haldia Petrochemicals Ltd., 171 Haldor Topsoe A/S, 154 Hall Chemical Company, The, 231... 

Balog, M., Schieber, M., Michman, M., andPatai, S., Chemical V apor Deposition and Characterization ofHf02 Films from Organo-Hafnium Compounds, Thin Solid Films, 41 247-259 (1977)... 

Chemical information from hafnium Mossbauer spectroscopy can primarily be deduced from the quadrupole-splitting parameter. In Table 7.4, we have listed the quadrupole coupling constants eQV for some hafnium compounds. Schafer et al. 

Haber process, 22 792 Hackling, 77 292 Hackmanite, color, 7 338 Haemanthamine, 2 87 Hafnium (Hf), 73 78-97 26 637. See also Hafnium compounds analytical methods for, 73 87-88 chemical properties of, 73 80 economic aspects of, 73 86-87 health and safety factors related to, 73 88... 

The discovery of the element hafnium provides a further example of a missed opportunity to turn scientific achievement into practical application. Hafnium was discovered at Niels Bohr s institute in Copenhagen in 1923 and quickly turned out to be fairly abundant and of potential industrial interest. However, no Danish chemical company seems to have taken an interest in the discovery. The two discoverers, Hevesy and Dirk Coster, sold the patent rights to the Philips firm in the Netherlands. Philips at once took out several patents on the use of hafnium compounds and developed methods for applying the metal in electrodes, filaments and fireproof enamels. ... 

P.J. Spencer in Hafnium Physico-Chemical Properties of its Compounds and Alloys , K.L. Komarek (ed.). Atomic Energy Rev. Spec. Issue 8, IAEA, Vienna, 1981, pp. 108-110. 

Element 104, the first transactinide element, is expected to have chemical properties similar to those of hafnium. It would, for example, form a relatively volatile compound with chlorine (a tetrachloride). 

Hafnium had lain hidden for untold centuries, not because of its rarity but because of its dose similarity to zirconium (16), and when Professor von Hevesy examined some historic museum specimens of zirconium compounds which had been prepared by Julius Thomsen, C. F. Rammelsberg, A. E. Nordenskjold, J.-C. G. de Marignac, and other experts on the chemistry of zirconium, he found that they contained from 1 to 5 per cent of the new element (26, 27). The latter is far more abundant than silver or gold. Since the earlier chemists were unable to prepare zirconium compounds free from hafnium, the discovery of the new element necessitated a revision of the atomic weight of zirconium (24, 28). Some of the minerals were of nepheline syenitic and some of granitic origin (20). Hafnium and zirconium are so closely related chemically and so closely associated in the mineral realm that their separation is even more difficult than that of niobium (columbium) and tantalum (29). The ratio of hafnium to zirconium is not the same in all minerals. 

Due to its 5t/-6.v- electron configuration, hafnium forms tctravalent compounds readily, although the Ilf1 ion docs not exist as such In aqueous solution except at very low pH values, Ihe common cation being HfO lor Hf OH)i ) and many of the tctravalent compounds are partly covalent. There are also less stable Hf(lll) compounds, There is close similarity in chemical properties to those of zirconium due to the similar outer electron configuration (4identical ionic radii (ZrJ is 0.80 A) the relatively low value for Hf being due lo the Lanthanide contraction. 

The similarity in size causes a very close similarity in chemical properties hafnium and zirconium compounds occur together in nature and are very difficult to distinguish from each other, and other pairs of elements following zirconium and hafnium resemble each other more closely than is usual for two successive members of a family. 

Element 104. (eka-hafnium) is predicted to resemble its homolc hafnium (element 72) in its chemical properties. It is expected to be predominantly tetra-positive, both in aqueous solution and in its solid compounds, although it should exhibit sohd halides and perhaps aqueous ions of the +2 and +3 oxidation state as well. 

In the modified Hill system as used by Chemical Abstracts today the arrangement of symbols in formulas is alphabetic, except that in carbon compounds C always comes first, followed immediately by H if hydrogen is also present. For deuterium and tritium compounds, D and T, respectively, are used. These are placed alphabetically in formulas the exception in arrangement made for H is not extended to include these isotopes, Glutamic-d acid is therefore written C5H8DNO4, The names of certain elements and their respective symbols are given preference over former names. The preferred names are astatine, beryllium, niobium, hafnium, and promethium (but not wolfram) (7). 

There has been tremendous growth in the chemistry of zirconium and hafnium since the 1960s. Many of the developments have been the result of efforts to uncover new applications. One of the major driving forces has been the rising importance of single-site alkene polymerization catalysis and catalysis in general. Other motivations have included a variety of strategies to develop molecular compounds as precursors to specific solid-state materials. In all cases, the fundamental chemical issues often are reduced to the development of new coordination chemistry. 

The amount of hafnium-free zirconium used in nuclear applications is much smaller than the ordinary commercial uses of zirconium metal and compounds, for which costly removal of hafnium is not required. Zirconium metal is used in corrosion-resistant equipment for chemical... 

Because of the effects of the lanthanide contraction, both the atomic radii of Zr and Hf (1.45 and 1.44 A, respectively) and the radii of the Zr4+ and Hf4+ ions (0.74 and 0.75 A, respectively) are virtually identical. This has the effect of making the chemical behavior of the two elements extremely similar, more so than for any other pair of congeneric elements. The chemistry of hafnium has been studied less than that of zirconium but only small differences, e.g., in solubilities and volatilities of compounds, are to be expected or found. 

Element 104, the first transactinide element, is expected to have chemical properties similar to those of hafnium. It would, for example, form a relatively volatile compound with chlorine (a tetrachloride). The Soviet scientists have performed experiments aimed at chemical identification, and have attempted to show that the 0.3-s activity is more volatile than that of the relatively nonvolatile actinide trichlorides. This experiment does not fulfill the test of chemically separating the new element from all others, but it provides important evidence for... 

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