Alkali-earth metal

With the alkali earth metals s-block elements, the bonding is typically ionic in nature. However Mg can have covalent type bonding, and beryllium atoms bond with some polarization. 

The development of cryptands and crown ethers is a relatively new endeavor in the history of chemistry, and has led to the field of supramolecular chemistry. Cryptands and crown ethers have been developed with the intention of selectively chelating with the s-block elements. Some of these are radioactive, and this is one way they can be removed from water supplies. They are called crown ethers because they look like a spiky crown with a central space that can be filled with a metal. An ether s an organic molecule that has 

For these s-block elements, the stability of complexes is often affected by the difference in the size of the ionic radii relative to the cation and anion pair. Large anions are generally better stabilized by large cations for example, barium peroxide is more stable than beryllium peroxide. In fact, the barium peroxide compound is so stable that it forms spontaneously in air. 

There are several important covalent metal-alkali compounds that serve as catalysts for reactions between carbon atoms. One example is Grignard reagents, made from the bonding between lithium and alkyl groups. These are useful for metathesis reactions, whereby alkyl groups can be linked together. Organic chemists use this to form C-C bonds. 

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The formation of more replaced compounds in studied conditions is not have place. Maximal yield on surface polyurethane foam of salts is observed by pH 2-6. By pH<2 the equilibrium ionic exchanges was displaced left and by pH<0,5 the sorbent practical completely was regenerated. It was studied the influence of the weight of sorbent, the nature of cations of light alkali and alkali earth metals and any other factors on the coefficient concentration ofM(I). 

Using BrF3 solutions, Gutmann and Emeleus [70] prepared a large number of hexafluoroniobates and hexafluorotantalates of alkali and alkali earth metals. 

IR absorption spectra of several fluorotantalates of alkali and alkali earth metals prepared by hydrofluoride synthesis are presented in Fig. 17. 

The method is based on the complete dissolution of the raw material. Only alkali earth metals and rare earth metals that form insoluble salts do not usually provide any significant preliminary concentration of the material during decomposition. In addition, concentration of tantalum and niobium in the final solution yielding by dissolution depends on the composition of the raw material. 

Rare earth metals, as well as alkali earth metals, can be used as oxygen getters in the purification of tantalum powder. Osaku and Komukai [608] developed a method for the production of tantalum and niobium metal powder by a two-step reduction of their oxides. The second step was aimed at reducing the oxygen content and was performed by thermal treatment with the addition of rare metals. The powder obtained by the described method is uniform, had a low oxygen level and was suitable for application in the manufacturing of tantalum capacitors. 

T.F. Levchishina, R.L. Davidovich, Complex fluorides of zirconium, hafnium, niobium and tantalum with cations of alkali earth metals, Dep. VINITI, No 3595-75 Dep 1975. 

The sites for complex formation in DMSO with inorganic salts depend remarkably on the nature of the metals involved in the salts. The alkali or alkali earth metallic salts form a complex with the oxygen atom in DMSO while Pd(II) or Pt(II) associates strongly at the sulphur atom. The IR frequency of the S—O bond of DMSO shifts to even lower wave numbers when associated with such metal cations as Li+, Na+ or Ca+ +34. On the other hand, in the case of Pd(II) or Pt(II), the S—O frequency appears at higher wave numbers, at around llOO-llAOcm 135. These different shifts for the S—O frequency afford a convenient diagnosis to determine whether the cation associates with the oxygen or the sulphur atom in DMSO. 

Heimann and Vogtle [38] synthesized triesters of glycerol with different ether carboxylic acids with a short alkyl chain. They have found that these hydrophilic lipids, in contrast with the fatty acid glycerol triesters, give complex-ation with alkali and alkali earth metal cations in an analogy of crown ethers. 

Experimental work can be difficult owing to both the high volatility of the metals and their reactivity toward O2 (e.g., alkali-metals, alkali-earth metals, rare earths). Once reaction begins it often is highly exothermic judging by the enthalpies of formation of borides. ... 

In solution this reaction is rather rapid but in the solid state autoxidation takes place much slower. Nevertheless, commercial sulfides and polysulfides of the alkali and alkali earth metals usually contain thiosulfate (and anions of other sulfur oxoacids) as impurities [6]. For all these reasons the chemistry of polysulfides is rather complex, and some of the earlier studies on polysulfides (prior to ca. 1960) are not very rehable experimentally and/or describe erroneous interpretations of the experimental results. 

Water-soluble sulfides like those of the alkah and alkali earth metals dissolve in H2O with hydrolysis to give strongly alkaline solutions ... 

In the present investigation we set before ourselves the task to check the influence of chlorids of different alkali and alkali-earth metals on the rate of the hydrolysis, ammonolysis and depolymerization of apple pectin in aqueous solution of ammonia. 

Krebs, Robert E. The history and use of our earth s chemical elements a reference guide. Westport (CT) Greenwood P, 1998. ix, 346p. ISBN 0-313-30123-9 A short history of chemistry — Atomic structure The periodic table of the chemical elements — Alkali metals and alkali earth metals - Transition elements metals to nonmetals — Metallics and metalloids - Metalloids and nonmetals — Halogens and noble gases - Lanthanide series (rare-earth elements) — Actinide, transuranic, and transactinide series... 

Metals are divided into light (also called alkali-earth metals) and heavy. All toxic metals are heavy metals except for beryllium and barium. Additionally, other categories of elements that are or may be significant chemically as dissolved species in deep-well-injection zones include the following ... 

Alkali-earth metals sodium, magnesium, potassium, calcium, and strontium... 

The common idea on the mechanisms governing the reduction of NO adsorbed species over LNT catalysts is that the regeneration process includes at first the release of NO, from the catalyst surface (i.e. from the alkali- or alkali-earth metal compound), followed by the reduction of the released NO to N2 or other products [11]. The reduction of the released NO in a rich environment is thought to occur according to the TWC chemistry and mechanisms in particular, it was suggested that NO is decomposed on reduced Pt sites [38], or that a direct reaction occurs between released NO species and the HC reductant molecules on the precious metal sites [39],... 

Di or trivalent cations are able to induce the dissociation of coordinated water molecules to produce acidic species such as MOH+ (or MOH2+ for trivalent metal cations) and H+. Several infrared studies concerning rare-earth or alkali-earth metal cation exchanged Y zeolites have demonstrated the existence of such species (MOH+ or MOH2+) [3, 4, 5, 6]. However, the literature is relatively poor concerning the IR characterization of these acidic sites for LTA zeolites. The aim of the present work is to characterize 5A zeolite acidity by different techniques and adsorption tests carried on 5A zeolite samples with different ion exchange. 

Prior to analysis, solutions from seven-day T/D tests on cuprous oxide (Cu20) and nickel metal powder (Ni) were passed through a column with iminodiacetate functional groups using an ammonium acetate buffer. The alkali and alkali earth metals are not bound to the column thereby separating the cations associated with the saltwater matrix from the transition metals of interest which are subsequently eluted with nitric acid and analysed by ICP-AES (inductively-coupled plasma-atomic emission spectrometry). 

Alkali cellulose, 4 716 Alkali earth metal nitrides, 17 206-207 Alkali flame-ionization detector (AFID), gas chromatography, 6 381 Alkali-gravity-viscosity (AGV) charts, for silicate glasses, 22 462, 463 Alkali halide disk method, 14 229 Alkali-immobile compounds, dye release from, 19 288... 

By the mid-nineteenth century, approximately sixty-five elements were known When Graham planned a chemistry course in the mid-nineteenth century, he divided the elements into "groups or natural families," based on their properties he divided the metals into nine "orders" distributed among three "classes" (alkalis and alkali-earths metals of earths and metals proper, divided according to affinity for oxygen).49 The classes of elements are not abruptly separated, he stated, but shade "into each other in their characters, like the classes created by the naturalists for the objects of the organic world. "50... 

The alkali earth metals and Eu and Yb a summary of their atomic and physical properties... 

Main atomic and physical properties of the alkali earth metals are summarized in Tables 5.7 and 5.8. Their typical electron configurations correspond to the outermost ns2 electrons. Alkali earth metals show relatively low 1st and 2nd ionization energies this can be related to the fact that almost without exception both the external 5 electrons take part together in bond formation whether the bond is ionic or covalent. 

Alkali and Alkali-Earth Metal Aikoxides, Brochure, Troisdorf-Oberlaar, Dynamit Nobel AG, 1974... 

Galli mentioned the addition of alkali-earth metals (mainly calcium) to the BGE to improve separation of organic acids. Calcium ions interact through the formation of complexes with different stabilities giving different mobilities. EDTA may also be used to form different complexes. Alternatively, EDTA may remove interfering compounds. 

As known (Addison and Logan 1964), anhydrons nitrates exhibit oxidizing properties. Their oxidizing activity increases from ionic nitrates with alkali and alkali-earth metal cations to covalent nitrates with transient metal cations. Oxidation reactions result in the formation of nitrogen-containing oxides. Depending on the kind of a nitrate salt and reaction conditions, one of these oxides can be predominant. Organic snbstrates can evidently serve as reductant. 

Alkali earth metals—Group 2 (llA), shades of white to subtle colors, malleable, machinable, and less active than alkali metals. They are all solids and have two electrons in their outer valence shell. 

In the metallic state, lithium is a very soft metal with a density of 0.534 g/cm. When a small piece is placed on water, it will float as it reacts with the water, releasing hydrogen gas. Lithium s melting point is 179°C, and it has about the same heat capacity as water, with a boiling point of 1,342°C. It is electropositive with an oxidation state of + 1, and it is an excellent conductor of heat and electricity. Its atom is the smallest of the alkali earth metals and thus is the least reactive because its valence electron is in the K shell, which is held closest to its nuclei. 

Sodium is produced by an electrolytic process, similar to the other alkali earth metals. (See figure 4.1). The difference is the electrolyte, which is molten sodium chloride (NaCl, common table salt). A high temperature is required to melt the salt, allowing the sodium cations to collect at the cathode as liquid metallic sodium, while the chlorine anions are liberated as chlorine gas at the anode 2NaCl (salt) + electrolysis —> Cl T (gas) + 2Na (sodium metal). The commercial electrolytic process is referred to as a Downs cell, and at temperatures over 800°C, the liquid sodium metal is drained off as it is produced at the cathode. After chlorine, sodium is the most abundant element found in solution in seawater. 

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