ALKALI ALKALINE EARTH METALS strontium used

Using the voltaic battery, Davy showed that the alkaline earths, like the caustic alkalis, were compounds containing oxygen and previously unknown metals. His characterization and naming of the alkaline earth metals followed his discovery of them barium, strontium, calcium, and magnesium are the names he invented for these metals. Like the names sodium and potassium, they are still in use today. 

Other. Insoluble alkaline-earth metal and heavy metal stannates are prepared by the metathetic reaction of a soluble salt of the metal with a soluble alkali—metal stannate. They are used as additives to ceramic dielectric bodies (32). The use of bismuth stannate [12777-45-6], Bi SnO SH O, with barium titanate produces a ceramic capacitor body of uniform dielectric constant over a substantial temperature range (33). Ceramic and dielectric properties of individual stannates are given in Reference 34. Other typical commercially available stannates are barium stannate [12009-18-6], BaSn03 calcium stannate [12013-46-6], CaSn03 magnesium stannate [12032-29-0], MgSn03 and strontium stannate [12143-34-9], SrSn03. 

The properties of hydrated titanium dioxide as an ion-exchange (qv) medium have been widely studied (51—55). Separations include those of alkali and alkaline-earth metals, zinc, copper, cobalt, cesium, strontium, and barium. The use of hydrated titanium dioxide to separate uranium from seawater and also for the treatment of radioactive wastes from nuclear-reactor installations has been proposed (56). 

This effect mostly occurs with alkali and alkaline earth metals. The low ionisation potentials of these elements cause them to be readily ionised in the flame with a resultant lowering of the population of ground state atoms and a suppression of sensitivity. The technique used to overcome this is to add an easily ionised salt such as potassium chloride to samples and standards. This ionises in preference to the analyte in the flame and enhances sensitivity. As an example, strontium, barium and aluminium are subject to ionisation in the flame. In water analyses, this is suppressed by adding potassium to the samples and standards so that the solution contains 2 000 mg l-1 potassium. 

Alkali metals lithium, sodium, potassium, rubidium, cesium, and francium. Metals such as sodium and potassium (the alkali metals) react violently with water—too violently to conduct experiments. The group 2 metals (also called alkaline earth metals) react less readily and can be used in the laboratory. Alkaline earth metals, including beryllium, magnesium, calcium, strontium, barium, and radium. 

Syntheses that exploit the solubility of the alkaline-earth metals in liquid ammonia have proven practical for alkoxide work, as they generate high yields, reaction rates, and purity (Table 8, Equation (3)). In a refinement of this approach, Caulton and co-workers have used dissolved ammonia in an ethereal solvent, usually THF, to effect the production of a number of alkoxides of barium, and this method has also been examined with calcium and strontium (Table 8, Equations (4a) to (4c)). Displacement reactions using alkali metal alkoxides and alkaline-earth dihalides (Table 8, Equation (5)), and between alkaline-earth hydrides or amides and alcohols (Table 8, Equations (6) and (7)), have been examined, but alkali-metal halide impurities, incomplete reactions, and unexpected equilibria and byproducts can affect the usefulness of these approaches. 

Alkaline earth metals are the six elements forming Group Ila in the Periodic Table beryllium (Be), magnesium (Mg), Calcium (Ca), Barium (Ba), Strontium (Sr), and Radium (Ra). Their oxides are basic (alkaline), especially when combined with water. Earth is a historical term applied to nonmetallic substances that are insoluble in water and stable to heating, and also the properties of the oxides. Hence, the term alkali earths is often used to describe these elements. 

Hydroxo salt is the term used for a group of complexes where the central atom of the complex anion is a metal to which hydroxyl ions are bound as ligands. The niunber of these ions depends on the normal coordination number of the metal. The cation of a hydroxo salt is usually an alkali metal, particularly sodium, or the alkaline earth metals barium, strontium and, in some cases, calciiun. Heavy-metal salts can be prepared from a few hydroxo anions via a double decomposition reaction. 

Liquid ammonia has certain solvent properties like those of water however, liquid ammonia will dissolve the alkali metals (sodium, potassium, etc.) and the heavier alkaline earth metals (calcium, strontium, barium) to give intensely blue, conducting solutions. The sodium solution is widely used as a reducing agent in organic syntheses. The unbalanced equation is presented in textbooks as follows ... 

Application of solid-liquid extraction in the field of Inorganic Chemistry can be illustrated by taking the examples of separation of (i) lithium chloride from the chlorides of other members of the alkali metal group and (ii) calcium nitrate from the nitrates of other members of the alkaline earth group. The solubilities of sodium chloride and potassium chloride are very small in -hexanol and 2-ethylhexanol, whereas the solubility of lithium chloride is large enough so that it can be separated from a mixture of the three chlorides by extraction with these solvents. Similarly, using a 50-50 per cent mixture of absolute ethanol and ether calcium nitrate can be removed from a mixture of the anhydrous nitrates of calcium, barium and strontium. 

A more common type of spectral interference in either emission or absorption measurements arises from the occurrence of band emission-spectra due to molecular species in the flame. (In fact, many elements can be measured by means of the band spectra of the molecules they form in certain flames.) Calcium and strontium, for example, exist partially as molecular hydroxides and oxides in a flame and emit bands in the vicinity of both the sodium and lithium resonance lines. When the alkaline-earth/alkali-metal ratio is high, the interference can become serious, unless a high-resolution monochromator is used. 

Determination of ages by the Sm/Nd method entails analyzing either individual minerals or cogenetic rock suites in which the ratios between the two are sufficiently different to define the slope of an isochron in coordinates of [ Nd/ Nd] and ] Sm/ Nd]. The method is especially suitable for mafic and ultramafic rocks, c the Rb/Sr method, which is best suited for acidic and intermediate igneous rocks enriched in rubidium and depleted in strontium. Since the rare earth elements are less mobile than the alkali metals and the alkaline earths, phenomena such as regional metamorphism have less effect on them. Hence, suitable rocks can be dated by the Sm/Nd method even if they have lost or gained rubidium and strontium and this makes the Sm/Nd method a useful complement to the R/Sr method. 

---