Beryllium compounds properties

Beryllium compounds are very toxic and must be handled with great caution. Their properties are dominated by the highly polarizing character of the Be2+ ion and its small size. The strong polarizing power results in moderately covalent compounds, and its small size limits to four the number of groups that can attach to the ion. These two features together are responsible for the prominence of the... 

Because of numerous similarities in their properties and reactions, aluminum and beryllium will be described together even though they are in different groups of the periodic table. Although it is not completely understood, there is some indication that the accumulation of aluminum in the brain may have some relationship to Alzheimer s disease, and beryllium compounds are extremely toxic. 

VH.16 BERYLLIUM, Be (At 9 01) Beryllium is a greyish-white, light but very hard, brittle metal. It dissolves readily in dilute acids. In its compounds beryllium is divalent, otherwise it resembles closely aluminium in chemical properties it also exhibits resemblances to the alkaline earth metals. The salts react acid in aqueous solution, and possess a sweet taste (hence the name glucinum formerly given to the element). Beryllium compounds are highly poisonous. 

The physicochemical properties of beryllium compounds and alloys have been reviewed subjects include phase diagrams, crystal structure, and density data on alloys and compounds, with a special section devoted entirely to halides and chalcogenides. ... 

BIOLOGICAL PROPERTIES metal will precipitate Ifom natural sulfates and carbohydrates some compounds dissolve in water, but most settle to the bottom most beryllium in soil does not move up to the surface or into the groundwater beryllium compounds of very low water solubility appear to predominate in soils highly persistent in water (half-life >200 days)... 

Describes the faeparation of pure material including the sulphate, chloride, acetyl-acetonate and basic acetate. States that the supposed new element noted by Kriiss and Moraht in beryllium compounds is a mixture of zinc and iron. Gives properties of the chloride, sulphate, acetyl-acetonate and basic acetate. By the analysis of seven samples of beryllium acetyl-acetonate and nine of basic acetate, obtained the atomic weight 9.113. Results on. sulphate unsatisfactory and the method im-reliable in the opinion of the author. 

Because of a pronounced amphoteric nature of beryllium, all attempts to obtain beryllium compounds in a sufficiently pure form were unsuccessful for a long time. As a result, many properties of the element and especially its valence and atomic mass were determined incorrectly. Consequently, the place of beryllium in the periodic table was not definitely found for a very long time. Only after it had been firmly established that beryllium is bivalent, that the formula of its oxide is BeO, and atomic mass is 9.01, was it once and for all placed in the upper box of the second group. A great contribution to that was made by the Russian scientist I.V. Avdeev. 

The small lithium Li" and beryllium Be ions have high charge-radius ratios and consequently exert particularly strong attractions on other ions and on polar molecules. These attractions result in both high lattice and hydration energies and it is these high energies which account for many of the abnormal properties of the ionic compounds of lithium and beryllium. 

Beryllium Halides. The properties of the fluoride differ sharply from those of the chloride, bromide, and iodide. BeryUium fluoride is essentiaUy an ionic compound, whereas the other three haUdes are largely covalent. The fluoroberyUate anion is very stable. 

Two other factors are noteworthy the deleterious effects on chemical and mechanical properties of small amounts of impurities residual from extraction of the metal, and its toxicity. The first of these factors is obviated by vacuum melting the raw metal (for purification) as an essential prerequisite to further processing. The toxicity of beryllium is essentially a pulmonary problem and great care must be taken in handling the finely divided metal or its compounds. In practice, this type of activity is usually carried out under well-ventilated conditions. Certain tolerance levels for atmospheric beryllium are now internationally accepted and merit careful study before work on beryllium is embarked upon. 

Beryllium, at the head of Group 2, resembles its diagonal neighbor aluminum in its chemical properties. It is the least metallic element of the group, and many of its compounds have properties commonly attributed to covalent bonding. Beryllium is amphoteric and reacts with both acids and alkalis. Like aluminum, beryllium reacts with water in the presence of sodium hydroxide the products are the beryl-late ion, Be(OH)42, and hydrogen ... 

Boron, a metalloid with largely nonmetallic properties, has acidic oxides. Aluminum, its metallic neighbor, has amphoteric oxides (like its diagonal neighbor in Group 2, beryllium). The oxides of both elements are important in their own right, as sources of the elements, and as the starting point for the manufacture of other compounds. 

Beryllium oxide shows excellent thermal conductivity, resistance to thermal shock, and high electrical resistance. Also, it is unreactive to most chemicals. Because of these properties the compound has several applications. It is used to make refractory crucible materials and precision resistor cores as a reflector in nuclear power reactors in microwave energy windows and as an additive to glass, ceramics and plastics. 

The study of coordination compounds of the lanthanides dates in any practical sense from around 1950, the period when ion-exchange methods were successfully applied to the problem of the separation of the individual lanthanides,131-133 a problem which had existed since 1794 when J. Gadolin prepared mixed rare earths from gadolinite, a lanthanide iron beryllium silicate. Until 1950, separation of the pure lanthanides had depended on tedious and inefficient multiple crystallizations or precipitations, which effectively prevented research on the chemical properties of the individual elements through lack of availability. However, well before 1950, many principal features of lanthanide chemistry were clearly recognized, such as the predominant trivalent state with some examples of divalency and tetravalency, ready formation of hydrated ions and their oxy salts, formation of complex halides,134 and the line-like nature of lanthanide spectra.135... 

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