Alkaline earth metals characteristics

For the chemistry of the heavier alkaline earth metals characteristic differences are observed. The motif of a hexagonal MeEg prism is as yet unknown for the phosphanediides of calcium. 

The three series of elements arising from the filling of the 3d, 4d and 5d shells, and situated in the periodic table following the alkaline earth metals, are commonly described as transition elements , though this term is sometimes also extended to include the lanthanide and actinide (or inner transition) elements. They exhibit a number of characteristic properties which together distinguish them from other groups of elements ... 

Europium and Yb display further similarity with the alkaline earth metals in dissolving in liquid ammonia to give intense blue solutions, characteristic of solvated electrons and presumably also containing [Ln(NH3)x]. The solutions are strongly reducing and decompose on standing with the precipitation of orange Eu(NH2)2 and brown Yb(NH2)2 (always contaminated with Yb(NH2)3) which are isostructural with the Ca and Sr amides. 

Electrons are not only charged, they also have a characteristic physicists call spin. Pairing two electrons by spin, which has two possible values, up or down, confers additional stability. Bei yllium (Be, atomic number 4) has two spin-paired electrons in its second shell that are easily given up in chemical reactions. Beryllium shares this characteristic with other elements in column two, the alkaline earth metals. These atoms also generally form ionic bonds. Boron... 

Table S. Hot-Pressing Characteristics of Alkaline-Earth Metal Borides...

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. 

The analysis of tetramethylammonium hydroxide (TMAH) solutions manufactured by SACHEM Inc. of Cleburne, Texas, includes the determination of trace elements. These elements cause less-than-optimum performance of integrated circuit boards manufactured by SACHEM s customers that use these solutions in their processes. Alkali and alkaline earth metals (e.g., Li, Na, K, Mg, Ca, and Ba) can reduce the oxide breakdown voltage of the devices. In addition, transition and heavy metal elements (e.g., Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ag, Au, and Pb) can produce higher dark current. Doping elements (e.g., B, Al, Si, P, As, and Sn) can alter the operating characteristics of the devices. In SACHEM s quality control laboratory, ICP coupled to mass spectrometry is used to simultaneously analyze multiple trace elements in one sample in just 1 to 4 min. This ICP-MS instrument is a state-of-the-art instrument that can provide high throughput and low detection Emits at the parts per thousand level. Trace elemental determination at the parts per thousand level must be performed in a clean room so that trace elemental contamination from airborne particles can be minimized. 

Reference has been made already to the existence of a set of inner transition elements, following lanthanum, in which the quantum level being filled is neither the outer quantum level nor the penultimate level, but the next inner. These elements, together with yttrium (a transition metal), were called the rare earths , since they occurred in uncommon mixtures of what were believed to be earths or oxides. With the recognition of their special structure, the elements from lanthanum to lutetium were re-named the lanthanons or lanthanides. They resemble one another very closely, so much so that their separation presented a major problem, since all their compounds are very much alike. They exhibit oxidation state + 3 and show in this slate predominantly ionic characteristics—the ions. LJ+ (L = lanthanide), are indeed similar to the ions of the alkaline earth metals, except that they are tripositive, not dipositive. 

General characteristics of alloys such as those presented in Fig. 3.3 have been discussed by Fassler and Hoffmann (1999) in a paper dedicated to valence compounds at the border of intermetallics (alkali and alkaline earth metal stannides and plumbides) . Examples showing gradual transition from valence compounds to intermetallic phases and new possibilities for structural mechanisms and bonding for Sn and Pb have been discussed. Structural relationships with Zintl phases (see Chapter 4) containing discrete and linked polyhedra have been considered. See 3.12 for a few remarks on the relationships between liquid and amorphous glassy alloys. 

When small amounts of alkali metals, alkaline earth metals, or their salts are introduced into a gaseous flame, flame reactions occur relatively easily at low temperatures.The liberated metal atoms are promoted to excited states and then return to their normal states. Radiation corresponding to the characteristic line spectra of the individual metal atoms is emitted as a result of this energy transition. Colored radiation discernible by the human eye, ranging from red to blue, is dependent on the type of metal atoms, as shown in Table 12AP- i... 

Fullerenes can be easily chemically reduced by the reaction with electropositive metals [1, 97-99], for example, alkali- and alkaline earth metals. The anions Cjq"" (n = 1-5) can be generated in solution by titrating a suspension of in liquid ammonia with a solution of Rb in liquid ammonia [100], whereupon the resulting anions dissolve. Monitoring of this titration is possible by detecting the characteristic NIR absorption of each anion by UV/Vis/NIR spectroscopy. The solubility of the alkali metal fullerides in the polar solvent NHj demonstrates their salt character. 

In spite of the overwhelming importance of the channel mechanism for the transport of alkali and alkaline earth metal ions in biological systems, only carrier transport has been studied extensively by chemists. Studies on ion channel mimics of simple structures have long been limited to antibiotic families of gramicidin, amphotericin B, and others. Several pioneers have reported successful preparation of non-peptide artificial channels. However, their claims have been based on kinetic characteristics observed for the release of metal ions through liposomal membrane and lacked the very critical proofs of channel formation. Such a situation was... 

Alkali metal silanides, characteristics, 2, 18 Alkali metal stannides, characteristics, 2, 23 Alkaline earth metals... 

In 1956 it was found that europium and ytterbium dissolve in liquid ammonia with the characteristic deep blue color known for the alkali and alkaline earth metals [36-40]. This behavior arises from the low density and high volatility of those metals compared to the other lanthanide elements [41]. Samarium, which normally also occurs in the divalent oxidation state, does not dissolve under... 

The characteristics of this group are that the elements possess a valence of 3, and that the oxides, M2O3, have but a weakly developed basic character. Boron, in fact, shows practically no base-forming properties, but forms rather a weak acid. The oxide of aluminum displays both basic and acidic properties that is, it is amphoteric. The remaining elements are more distinctly base-forming than aluminum, without, however, approaching in any way the alkaline earth metals in this respect. 

The Requirement of a Divalent Alkaline Earth Metal. Lime-treated corn produces a dough whose functional properties depend on the pasting characteristics of starch. The hydroxides of different alkaline earth metals were tested to determine whether they could replace calcium in the nixtamalization process. It was not possible to prepare tortillas with adequate sensory or mechanical properties from corn treated with... 

The sodium soap is soluble in water and a very small quantity suflices to produce a lather if the water is pure. If, however, it contains dissolved salts of calcium or magnesium the lather is destroyed by these, yielding the familiar insoluble curd, so characteristic of the action of hard water on soap. This curd is really the insoluble soap of the alkaline earth metal formed by double decomposition as shown in the two following equations, in which it is assumed the hardness is due to the presence of calcium carbonate and magnesium sulphate respectively. ... 

The possibility of measurement of Mg2+ concentration in a matrix complicated by alkali and alkaline earth metal ions has been explored by titration of 68 (5 x 10-5 M) in 1 1 MeOH/H20 solution (pH 7.2) containing Na+ (5 x 10 3 M), K+ (1 X 10-3 M), Ba2+ (1 x 10 3 M), Sr2 (1 x 1(T3 M), and Ca2+ (1 x 10-4 M). The titration was monitored via fluorescence.125 The fluorescence intensity reached a maximum at 1 equiv of Mg2+, indicating that fluorescent intensity could be directly correlated to Mg2+ concentration. The lack of interference from the other metal ions present can be a result of their lower binding constants with 68 and lower quantum yields of the charged complexes of 68 with Na+, K+, Ca2+, Sr2+, and Ba2+ at this pH. Thus, ligand 68 possesses characteristics of an efficient fluorescent chemosensor for Mg2+ and may find use in determining Mg2+ in biological samples and, if immobilized on a solid support, may be incorporated into sensory devices for measurement of Mg2+ concentrations in aqueous solutions. 

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