Zirconium compounds chemical properties

O. Kubaschewski, ed.. Zirconium Physico-Chemical Properties of its Compound and Alloys, International Atomic Energy Agency, Vieima, 1976, p. 8. 

Source International Atomic Energy Agency, Zirconium Physico-Chemical Properties of Its Compounds and Alloys, Atomic Energy Rev., Special Issue No. 6, 1976. 

C.B. Alcock, K.T. Jacob, S. Zador in Zirconium physoco-chemical properties of its compounds and alloys . Atomic Energy Review, Spec. Issue No. 6, O. Kubaschewski, Ed., IAEA, Vienna, 1976, pp. 7-65. 

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). 

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. 

Chapters S, 6, and 7 take up uranium, thorium, and zirconium in that order. Each chapter discusses the physical and chemical properties of the element and its compounds, its natural occurrence, and the processes used to extract the element from its ores, purify it, and convert it to the forms most useful in nuclear technology. 

CHEMICAL PROPERTIES most zirconium compounds are considered inert zirconium metal can react with hydrofluoric acid, aqua regia, and hot phosphoric acid attacked hy fused potassium hydroxide or potassium nitrate not attacked by cold, concentrated sulfuric or hydrochloric acid resistant to attack by nitric acid very resistant to corrosion oxidizes rapidly at 6°C nitrided slowly at 700°C compact form combines with oxygen, nitrogen, carbon, and the halogens on prolonged heating FP (NA) LFLAJFL (NA) AT (NA) HF (0.0 kJ/mol crystal at 25 C) Hf (21.0 kJ/mol at 2127.85K). 

In fact, the classification of chemical elements is valuable only in so far as it illustrates chemical behaviour, and it is conventional to use the term transition elements in a mote restricted sense. The elements in the irmer transition series from cerium (58) to lutetium (71) are called the lanthanoids those in the series from thorium (90) to lawrencium (103) are the actl-noids. These two series together make up the /block in the periodic table. It is also common to include scandium, yttrium, and lanthanum with the lanthanoids (because of chemical similarity) and to include actinium with the actinoids. Of the remaining transition elements, it is usual to speak of three main transition series from titanium to copper from zirconium to silver and from hafnium to gold. All these elements have similar chemical properties that result from the presence of unfilled d-orbltals in the element or (in the case of copper, silver, and gold) in the ions. The elements from 104 to 109 and the undiscovered elements 110 and 111 make up a fourth transition series. The elements zinc, cadmium, and mercury have filled d-orbltals both in the elements and in compounds, and are usually regarded as nontransition elements forming group 12 of the periodic table. 

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