Alkaline earth metals reactivity

Alkali Metal and Alkaline Earth Metal Reactivity... 

Cryptands, 7, 731-761 alkali metal complexes NMR, 7, 740 reactivity, 7, 743-744 alkaline earth complexes reactivity, 7, 743-744 anion complexes, 7, 747-748 applications, 7, 753-761 as biological models, 7, 753-754 bis-tren... 

The carbides of the lanthanoids and actinoids can be prepared by heating M2O3 with C in an electric furnace or by arc-melting compressed pellets of the elements in an inert atmosphere. They contain the C2 unit and have a stoichiometry MC2 or M4(C2)3. MC2 have the CaC2 structure or a related one of lower symmetry in which the C2 units lie at right-angles to the c-axis of an orthogonal NaCl-type cell. They are more reactive than the alkaline-earth metal... 

Salt-inclusion solids described herein were synthesized at high temperature (>500°C) in the presence of reactive alkali and alkaline-earth metal halide salt media. For single crystal growth, an extra amount of molten salt is used, typically 3 5 times by weight of oxides. The reaction mixtures were placed in a carbon-coated silica ampoule, which was then sealed under vacuum. The reaction temperature was typically set at 100-150 °C above the melting point of employed salt. As shown in the schematic drawing in Fig. 16.2, the corresponding metal oxides were first dissolved conceivably via decomposition because of cor-... 

In addition to having similar electron configurations, some blocks have common chemical characteristics, too. The block of elements on the far left of the illustration, for example, are all metals. The two groups in the block are called the alkali metals (first column) and alkaline earth metals (second column). The alkali metals are remarkably similar soft, silvery, highly reactive metals. The alkaline earth metals form another distinctive group that are much harder that the alkaline metals and have higher melting points. 

Elements have varying abilities to combine. Among the most reactive metals are the alkali metals and the alkaline earth metals. On the opposite end of the scale of reactivities, among the least active metals or the most stable metals are silver and gold, prized for their lack of reactivity. Reactive means the opposite of stable, but means the same as active. 

In the list of reactivities of metals, Table 7-1, are all alkali metals more reactive than all alkaline earth metals, or are all elements of both groups of metals more active than any other metals ... 

Metals which have been used (generally in inert or reducing atmosphere) as container materials are W (melting point 3422°C), Mo (2623°C), Pt (1769°C), Fe (1538°C), Ni (1455°C), Cu (1085°C), Au (1064°C), Ag (962°C). W and Mo do not react with many elements they must be protected however from air oxidation. Pt and Au cannot be used, owing to their reactivity, for melting metallic materials they are useful for other types of synthesis. Fe, of very high purity and with very low carbon content, could possibly be used for melting alkaline and alkaline earth metals and a number of their alloys. 

The collected papers of a symposium at Dallas, April 1956, cover all aspects of the handling, use and hazards of lithium, sodium, potassium, their alloys, oxides and hydrides, in 19 chapters [1], Interaction of all 5 alkali metals with water under various circumstances has been discussed comparatively [2], In a monograph covering properties, preparation, handling and applications of the enhanced reactivity of metals dispersed finely in hydrocarbon diluents, the hazardous nature of potassium dispersions, and especially of rubidium and caesium dispersions is stressed [3], Alkaline-earth metal dispersions are of relatively low hazard. Safety practices for small-scale storage, handling, heating and reactions of lithium potassium and sodium with water are reviewed [4],... 

Various nitro compounds have been condensed with carbonyl compounds in reactions catalyzed by alkaline earth metal oxides and hydroxides 145). It was found that the reactivities of the nitro compounds were in the order nitro-ethane > nitromethane > 2-nitropropane, and those of carbonyl compounds were propionaldehyde > isobutyraldehyde > pivalaldehyde > acetone > benzaldehyde > methyl propionate. Among the catalysts examined, MgO, CaO, Ba(OH)2, and Sr(OH)2, exhibited high activity for nitroaldol reaction of nitromethane with propionaldehyde. In reactions with these catalysts, the yields were between 60% (for MgO) and 26% (for Sr(OH)2) at 313 K after 1 h in a batch reactor. On Mg(OH)2, Ca(OH)2, and BaO, the yields were in the range of 3.8% (for BaO) and 17.5% (for Mg(OH)2). Investigation of the influence of the pre-treatment... 

As demonstrated in previous sections, unique reactivity and selectivity have been often observed in aqueous media, but one of the big issues is the stability of catalysts in water. To overcome this, efficient catalysts that are stable and can work well in aqueous media were searched for, and metal hydroxides were found. With the exception of alkaline and alkaline earth metal hydroxides, these have not... 

Alkyl derivatives of the alkaline-earth metals have also been used to initiate anionic polymerization. Organomagnesium compounds are considerably less active than organolithiums, as a result of the much less polarized metal-carbon bond. They can only initiate polymerization of monomers more reactive than styrene and 1,3-dienes, such as 2- and 4-vinylpyridines, and acrylic and methacrylic esters. Organostrontium and organobarium compounds, possessing more polar metal-carbon bonds, are able to polymerize styrene and 1,3-dienes as well as the more reactive monomers. 

Lithium metal is highly reactive but less so than other alkah metals. Its chemical properties, however, are more like those of the alkaline earth metals. 

The alkali and alkaline earth metals - such as sodium, potassium, barium, and calcium — would make excellent high-energy fuels, but, except for magnesium, they are too reactive with moisture and atmospheric oxygen. Sodium metal, for example, reacts violently with water and must be stored in an inert organic liquid, such as xylene, to minimize decomposition. 

Starting on the far left of the periodic table is Group lA, also known as the alkali metals. These most metallic of the elements are very reactive, meaning they tend to combine with other elements. They re found naturally in a bonded state, never in a pure state. Reactivity increases as you move down the periodic table. Group llA is called the alkaline earth metals. Just like the alkali metals, the alkaline earth metals cire highly reactive. 

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