Alkali negative ions

The structure of mica consists of two Si2052 sheets bonded together by alkali ions. There are layers of positive Al+3 and Mg+2 ions and negative O 2 and OFT1 ions on the outside of the double sheet. 

V. The Alkaline Earth Atoms and Alkali Negative Ions... 

V. THE ALKALINE EARTH ATOMS AND ALKALI NEGATIVE IONS... 

Nearly all the ions show some temperature dependence in aqueous solution, but at least for the tetraalkylammonium ions, very little in methanol solutions (Figure 4). Instead of increasing, B decreases with increasing size for the alkali metal and halide ions. The negative values of B indicate that most of these ions actually decrease the viscosity upon their addition to water. The B coefficients for the tetraalkylammonium ions increase with increasing size but for the larger ions, B is much larger in aqueous than in methanol solutions and extremely temperature dependent in aqueous solution. 

An example of this behavior is shown in Fig. 4.2, where the positive-ion and negative-ion ESI-MS spectra of a compoimd are shown with two catboxyhc acid functions, analyzed as di-potassium salt in a mobile phase containing ammonium acetate. In positive-ion mode, both the ammoniated molecule [M+NHJ+ and the potassiated molecule [M+K]" (or the H+/K -exchange product [(M-H+K)+H]+) are observed, whereas in negative-ion mode, the H+/K+-exchange product [(M-H+K)-H] is observed next to the deprotonated molecule [M-H] . Thus, apparent alkali metal ion adducts may be observed in negative-ion ESI-MS as well. 

Mononucleotides can be analyzed in either positive-ion or negative-ion using condensed-phase ionization techniques like TSI-MS, ESI-MS, and MALDI-MS. In positive-ion mode, [M+H]+- and (series of) [(M-H+Alkali)+H] -ions due to HVAlkah -exchange ate observed. In negative-ion mode, which actually is to be preferred, [M-H] - as well as (series of) [(M-H+Alkali)-H] -ions ate observed. The MS analysis of nucleobases, mono-nucleosides, nucleotides, and DNA adducts has recently been reviewed [268]. 

Miller T M, Leopold D G, Murray K K and Lineberger W C 1986 Electron affinities of the alkali halides and the structure of their negative ions J. Chem. Phys. 85 2368-75... 

Phenol condenses with phthahc anhydride in the presence of concentrated sulphuric acid or anhydrous zinc chloride to yield the colourless phenolphthalein as the main product. When dilute caustic alkah is added to an alcoholic solution of phenolphthalein, an intense red colouration is produced. The alkali opens the lactone ring in phenolphthalein and forms a salt at one phenolic group. The reaction may be represented in steps, with the formation of a h3q)othetical unstable Intermediate that changes to a coloured ion. The colour is probably due to resonance which places the negative charge on either of the two equivalent oxygen atoms. With excess of concentrated caustic alkali, the first red colour disappears this is due to the production of the carbinol and attendant salt formation, rendering resonance impossible. The various reactions may be represented as follows ... 

The material evaporated by the laser pulse is representative of the composition of the solid, however the ion signals that are actually measured by the mass spectrometer must be interpreted in the light of different ionization efficiencies. A comprehensive model for ion formation from solids under typical LIMS conditions does not exist, but we are able to estimate that under high laser irradiance conditions (>10 W/cm ) the detection limits vary from approximately 1 ppm atomic for easily ionized elements (such as the alkalis, in positive-ion spectroscopy, or the halogens, in negative-ion spectroscopy) to 100—200 ppm atomic for elements with poor ion yields (for example, Zn or As). 

Some metals are amphoteric. That is, they form simple cations (in acid solutions) and soluble oxyanions (in alkaline solution) only in the mid-pH range is a protective film stable. Since cathodic protection produces alkali at the structure s surface, it is important to restrict the polarisation, and thereby the amount of hydroxyl ion produced, in these cases. Thus both lead and aluminium will suffer cathodic corrosion under cathodic protection if the potential is made excessively electro negative. 

The scheme of the interaction mechanism (Equation 88) testifies to an electro-affinity of MeFe" ions. In addition, MeFe" ions have a lower negative charge, smaller size and higher mobility compared to MeF6X(n+1> ions. The above arguments lead to the assumption that the reduction to metal form of niobium or tantalum from melts, both by electrolysis [368] and by alkali metals, most probably occurs due to interaction with MeF6 ions. The kinetics of the reduction processes are defined by flowing equilibriums between hexa-and heptacoordinated complexes. 

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