Beryllium binary compounds

It is also shown that theoretically a binary compound should have the sphalerite or wurzite structure instead of the sodium chloride structure if the radius ratio is less than 0.33. The oxide, sulfide, selenide and telluride of beryllium conform to this requirement, and are to be considered as ionic crystals. It is found, however, that such tetrahedral crystals are particularly apt to show deformation, and it is suggested that this is a tendency of the anion to share an electron pair with each cation. 

Although sulphur in the compact form appears to be a comparatively inactive clement, yet when in a fine state of division it reacts with many metals, and at elevated temperatures it combines directly with nearly all other elements (exceptions being nitrogen, iodine, beryllium, gold, platinum and iridium) to form stable binary compounds, the reactions often occurring with great vigour. 

The most common moderators are substances of low atomic weight such as heavy water (deuterium oxide) or graphite. Hydrides (binary compounds corrtaining hydrogen), hydrocarborrs, and beryllium and beryllium oxide have also been used as moderators in certain specialized kinds of reactors. 

Binary compounds are formed with all nonmetallic elements, many by direct combination. Beryllium is exceptional as its coordination is almost always tetrahedral, giving structures that may be regarded as polymeric rather than highly ionic. Thus BeO has the wurtzite structure (see Topic D3). BeF2 is... 

When a metal cation and a non-metal anion form a compound, they are called metal-non-metal binary compounds. Metals with ions of only 1+, 2+, or 3+ charges in groups I A, II A, and III A are called monoatomic, diatomic and polyatomic ions respectively. Lithium, potassium, and cesium all have a 1+ charge. Beryllium and strontium, in group IIA, are named with the same rules. However, when you name elements in groups IVA-VIIA, where anions of-1, —2, or -3 anions are formed, then ide is added to the name. 

Silicides are binary compounds of metals and silicon. Formulas are difficult to predict, and the bizarre stoichiometries often appear to be the reaction products found on freshman examinations. Silicides of most representative metals except beryllium are known, and most of the transition elements except silver, gold, and a few others form various silicides. The heavy metals mercury, thallium, lead, and bismuth do not react with silicon indeed, the molten metals are not even miscible with liquid silicon. 

Occurrence of three scandium-beryllium intermetallic compounds and their crystal structures are the only data existing about the Sc-Be binary system. Their characteristics are presented in table 2. Gschneidner and Calderwood (1987) reviewed all available papers on scandium-beryllium binary alloys. 

The nature of a binary hydride is related to the characteristics of the element bonded to hydrogen (Fig. 14.8). Strongly electropositive metallic elements form ionic compounds with hydrogen in which the latter is present as a hydride ion, H. These ionic compounds are called saline hydrides (or saltlike hydrides). They are formed by all members of the s block, with the exception of beryllium, and are made by heating the metal in hydrogen ... 

The mass attenuation coefficient values of the elements are available in the literature [46]. Therefore, the mass attenuation coefficient of a compound can be calculated. Thus and (in Eq. 15) can be calculated provided the molecular formulas of components 1 and 2 are known. It is then possible to calculate the intensity ratio, /u/(/ii)o> as a function of xx. This ratio can also be experimentally obtained. The intensity of peak i of a sample consisting of only 1 is determined [(/ii )o] This is followed by the determination of the intensity of the same peak in mixtures containing different weight fractions of 1 and 2. This enables the experimental intensity ratio, /n/(/n)o, to be obtained as a function of xx. The principles discussed above formed the basis for the successful analyses of quartz-beryllium oxide and quartz-potassium chloride binary mixtures [45]. 

Monatomic ions Binary ionic compounds are composed of positively charged monatomic ions of a metal and negatively charged monatomic ions of a nonmetal. A monatomic ion is a one-atom ion, such as Mg + or Br . Table 7.7 indicates the charges of common monatomic ions according to their location on the periodic table. What is the formula for the beryllium ion The iodide ion The nitride ion ... 

Write the formulas of the binary hydrides for the second-period elements (LiH to HF). Illustrate the change from ionic to covalent character of these compounds. Note that beryllium behaves differently from the rest of Group 2A metals (see p. 344). 

The main features of the binary phase diagrams of elements of column IIA and rare earths or actinides are reported in figs. 8-12. The formation of intermetallic compounds is observed with beryllium and magnesium. The stoichiometry and the structures of the compounds are reported in figs. 13 and 14 for Be and Mg respectively. Table 1 lists the characteristics of the observed structures. 

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