Beryllate ion

Write the equations of the reactions and explain the occurring-processes. What is the coordination number of beryllium in sodium beryllate What type of orbital hybridization occurs when the beryllate ion forms and what spatial configuration does this correspond to ... 

Sodium hydroxide solution white gelatinous precipitate of beryllium hydroxide, readily soluble in excess of the precipitant, forming tetrahydroxo-beryllate ion, [Be(OH)4]2 on boiling the latter solution (best when largely diluted), beryllium hydroxide is reprecipitated (distinction from aluminium). The precipitate is also soluble in 10 per cent sodium hydrogen carbonate solution (distinction from aluminium). 

Addition of the OH ion to BeCl2 or other beryllium solutions gives the hydroxide. This is amphoteric, and in alkali solution the beryllate ion, probably [Be(OH)4]2, is obtained. When these solutions are boiled, the most stable of several polymorphs of the hydroxide can be crystallized. 

Has a diagonal relationship with Al. It is the only member of the group that, like Al, reacts in aqueous NaOH. In strongly basic solution, it forms the beryllate ion, [Be(OH)4] . 

FIGURE 14.20 An emerald is a crystal of beryl with some Cr + ions, which are responsible for the green color. 

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 ... 

Emerald, Cr " doped beryl, has a beryl structure with the Cr " impurity ions in highly distorted octahedron sites. The discovery of lasing action in emerald stimulated investigation of its luminescence properties. It was established that its tuning range is approximately 730-810 nm, while luminescence consists of a narrow line at 684 nm and a band peaking at 715 nm with similar decay times of 62 ps. The relative intensities of those line and band are different in a- and 7T-polarized spectra (Fabeni et al. 1991). 

In optical spectra of emerald (Neuhaus, 1960 Poole, 1964 Wood and Nassau, 1968 Schmetzer and Bank, 1981), Cr3+ CF bands are located near 16,130 cm-1 and 23,530 cm-1 and are assigned to cations in octahedral sites. Similar bands for octahedral V3+ ions in beryl occur around at 16,000 cm-1 and 23,800 cm-1 (Beckwith and Troup, 1973 Schmetzer, 1982 Ghent and Lucchesi, 1987). Spectral features of pink and red beryls in the region 18,000-20,000 cm-1 (Wood and Nassau, 1968) may originate from crystal field transitions in Mn3+ ions in morganite. 

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