Ionic compounds hydrides

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 ... 

Metals, intermetallic compounds and alloys generally react with hydrogen and form mainly solid metal-hydrogen compounds. Hydrides exist as ionic, polymeric covalent, volatile covalent and metallic hydrides. 

The meso-ionic l,2,4-triazol-3-ones (200) are stable to acid, but alkaline hydrolysis gives 1,4-disubstituted semicarbazides. They do not normally participate in 1,3-dipolar cycloadditions, but the meso-ionic 1,4-diphenyl-l,2,4-triazol-3-one (200, R = R = Ph, R = H) and benzyne yielded 2-phenylindazole. 1,2,4-Triazolium salts (211) are formed with triethyloxonium tetrafluoroborate. Reduction of the meso-ionic compound 200, R = Me, R = R = Ph, with lithium aluminum hydride gives the triazolidinone 212. ... 

It has been shown in Chapter VI that the stability of most complexes formed by two halides, oxides or hydrides follows the rules for complex formation of two ionic compounds. The formation of the complex ions BFt and NH " was described as an addition of the ions F and H+ to the molecules BF3 and NH3, caused by the attraction of the highly-charged ions B3+ and N3-. However, this complex formation can be given quite a different interpretation, and it can be argued that F ions combine with BF3 because, in this process, the octet of the B atom is completed... 

The hydrides, oxides and nitrides of the elements of the first three groups of the periodic system all behave as normal ionic compounds. They all show normal valencies, they crystallize in coordination lattices, do not show any metallic conductivity and, in so far as an estimate can be made of their heats of formation, they agree fairly well with the values to be expected for ionic compounds. 

Lithium hydride can be regarded as a saltlike ionic compound, Li H. Electrostatic attractions between oppositely charged ions in the crystal lattice... 

In earlier chapters, we saw examples of how the metallic or nonmetallic character of an element affects its chemistry. Metals tend to form ionic compounds with nonmetals, whereas nonmetals tend to form covalent, molecular compounds with one another. Thus, binary metallic hydrides, such as NaH and CaH2, are ionic solids with high melting points, and binary nonmetallic hydrides, such as CH4, NH3, H20, and HF, are covalent, molecular compounds that exist at room temperature as gases or volatile liquids (Section 14.5). 

Write the formulas for the following ionic compounds (a) lithium hydride (b) calcium bromate (c)chromium(II) oxide id) thorium(IV) perchlorate (e) nickel phosphate if) zinc sulfate. 

Most of the Group IA and IIA metals react with hydrogen to form metal hydrides. For all of the metals in these two groups except Be and Mg, the hydrides are considered to be ionic or salt-like hydrides containing H ions (see Chapter 6). The hydrides of beryllium and magnesium have considerable covalent character. The molten ionic compounds conduct electricity, as do molten mixtures of the hydrides in alkali halides, and during electrolysis of the hydrides, hydrogen is liberated at the anode as a result of the oxidation of H ... 

For metal hydride clusters, much less is known about electronic and geometrical size effects, except for very small clusters that can be relatively easily traced with computational methods. Results on other ionic compounds, such as ZnS clusters, indicate less well defined size effects, and only for small cluster sizes [11]. As the size dependence will be clearly different than for metal clusters, potentially there is a large influence of size on the stability differences between small hydride and the corresponding metal clusters. However, the practical impact of these effects is probably limited, as in the bulk experimental preparation of light metal (hydride) clusters, generally, polydisperse samples are obtained, and hence pronounced effects of... 

Examples of Sb—H bond formation by reactions of Sb compounds with either covalent or ionic binary hydrides are rare. The alkynlstibine, n-Bu,SbC=CH, reacts... 

The hydrides formed in reaction (a) may be classified as (1) saline or ionic hydrides, (2) metallic hydrides and (3) covalent hydrides. The saline hydrides include the hydrides of the alkali and alkaline-earth metals, except BeHj, which is covalent. Transition metals form binary compounds with hydrogen that are classified as metallic hydrides including rare-earth and actinide hydrides. Intermetallic compound hydrides, such as TiFeHj and LaNijH, may be thought of as pseudobinary metallic hydrides. 

A review of the chemistry of Group III complexes shows that many of the concepts of Werner s coordination chemistry may be applied to these elements. Furthermore, the differences observed in the complexing behavior between ammonia and trimethylamine refiect fundamental differences in the amines. Ammonia tends to give ionic compounds, whereas trimethylamine tends to give non-ionic products. Trends observed with the metal halides can be extrapolated into hydrides of boron, aluminum, and gallium. An extension of Werner s concepts provides a significant... 

H has, of course, only one electron in a Is orbital. Li has three - a full Is shell and one electron in the 2s orbital. Li is also very electropositive so its 2s orbital is high in energy (much higher than that of F - see the answer to Problem 3). The result is that lithium gives its 2s electron to the Is orbital of H and an ionic compound results with both ions having the same electronic configuration Is. The hydrides of the alkali metals are useful sources of hydride ion (H ). 

As pure substances, Group 1A or alkali metals are soft metallic solids with low densities and low melting points. They easily form 1+ cations. They are highly reactive, reacting with most nonmetals to form ionic compounds. Alkali metals react with hydrogen to form hydrides such as NaH. Alkali metals react exothermically with water to produce the metal hydroxide and hydrogen gas. In nature, alkali metals exist only in compounds. 

To name an ionic compound, just put tire cation name in front of the anion name as in barium sulfate (BaS04) or sodium hydride (NaH). 

The structures of the hydrides of the Group 1 and 2 elements are typical of ionic compounds because the H ion is compact and has a well-defined radius. ... 

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