Alkaline earth metals barium

Figure 4.3 Doctors illuminate the intestines of a patient with the help of the alkaline earth metal barium. The patient drinks a concoction of barium sulfate that lines the stomach and intestines. Barium s chemical properties allow it to absorb X-rays, highlighting any problem areas.

Like other alkaline earth metals, barium is a soft, silvery white metal. Discovered by Humphrey Davy in 1808, its primary sources are witherite, which is a type of barium carbonate (BaC03), and baryte, a type of barium sulfate (BaS04). 

PHENYL BROMIDE (108-86-1) C HsBr Flammable, light-sensitive liquid. Forms explosive mixture with air (flash point 124°F/51°C Fire Rating 2). Incompatible with strong oxidizers, alkaline earth metals (barium, calcium, magnesium, strontium, etc.), metallic salts, with risk of violent reactions. May accumulate static electrical charges may cause ignition of its vapors. On small fires, use dry chemical powder (such as Purple-K-Powder), foam, or COj extinguishers. 

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. 

The precipitation capacity of sodium rhodizonate is particularly interesting within the group of the alkaline earth metals. Barium gives a red-brown precipitate of barium rhodizonate. Strontium salts react in the same way with rhodizonates, but calcium salts do not. Under suitable conditions, however, barium may be identified in the presence of strontium. The rhodizonate test is thus recommended for the detection of barium within the ammonium carbonate (alkaline earth) group, or for its detection when bivalent heavy metals are known to be absent. 

Group IIB and know that this means the group of elements zine. cadmium and mercury, whilst Group IIA refers to the alkaline earth metals beryllium, magnesium, calcium, barium and strontium. 

The elements in Group II of the Periodic Table (alkaline earth metals) are. in alphabetical order, barium (Ba). beryllium (Be), calcium (Ca). magnesium (Mg), radium (Ra) and strontium (Sr). 

Strontium [7440-24-6] Sr, is in Group 2 (IIA) of the Periodic Table, between calcium and barium. These three elements are called alkaline-earth metals because the chemical properties of the oxides fall between the hydroxides of alkaU metals, ie, sodium and potassium, and the oxides of earth metals, ie, magnesium, aluminum, and iron. Strontium was identified in the 1790s (1). The metal was first produced in 1808 in the form of a mercury amalgam. A few grams of the metal was produced in 1860—1861 by electrolysis of strontium chloride [10476-85-4]. 

Strontium has a valence of +2 and forms compounds that resemble the compounds of the other alkaline-earth metals (see Barium compounds Calcium compounds). Although many strontium compounds are known, there are only a few that have commercial importance and, of these, strontium carbonate [1633-05-2] SrCO, and strontium nitrate [10042-76-9], Sr(N03)2, are made in the largest quantities. The mineral celestite [7759-02-6], SrSO, is the raw material from which the carbonate or the nitrate is made. 

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 alkah—metal stannate. They are used as additives to ceramic dielectric bodies (32). The use of bismuth stannate [12777-45-6] Bi2(Sn02)3 5H20, 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] BaSnO calcium stannate [12013 6-6] CaSnO magnesium stannate [12032-29-0], MgSnO and strontium stannate [12143-34-9], SrSnO. ... 

The properties of hydrated titanium dioxide as an ion-exchange (qv) medium have been widely studied (51—55). Separations include those of alkaH 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). 

Composite Oxyalkoxides. Composite oxyalkoxides can be prepared by reaction of tetraalkyl titanates and alkaline-earth metal hydroxides. These oxyalkoxides and their derivatives can be hydroly2ed and thermally decomposed to give alkaline-earth metal titanates such as barium titanate (150). 

Barium [7440-39-3] Ba, is a member of Group 2 (IIA) of the periodic table where it Hes between strontium and radium. Along with calcium and strontium, barium is classed as an alkaline earth metal, and is the densest of the three. Barium metal does not occur free in nature however, its compounds occur in small but widely distributed amounts in the earth s cmst, especially in igneous rocks, sandstone, and shale. The principal barium minerals are barytes [13462-86-7] (barium sulfate) and witherite [14941-39-0] (barium carbonate) which is also known as heavy spar. The latter mineral can be readily decomposed via calcination to form barium oxide [1304-28-5] BaO, which is the ore used commercially for the preparation of barium metal. 

Alkaline-earth metals are often deterruined volumetricaHy by complexometric titration at pH 10, using Eriochrome Black T as indicator. The most suitable complexing titrant for barium ion is a solution of diethylenetriaminepentaacetic acid (DTPA). Other alkaline earths, if present, are simultaneously titrated, and in the favored analytical procedure calcium and strontium are deterruined separately by atomic absorption spectrophotometry, and their values subtracted from the total to obtain the barium value. 

BeryUium reacts with fused alkaU haUdes releasing the alkaU metal until an equUibrium is estabUshed. It does not react with fused haUdes of the alkaline-earth metals to release the alkaline-earth metal. Water-insoluble fluoroberyUates, however, are formed in a fused-salt system whenever barium or calcium fluoride is present. BeryUium reduces haUdes of aluminum and heavier elements. Alkaline-earth metals can be used effectively to reduce beryUium from its haUdes, but the use of alkaline-earths other than magnesium [7439-95-4] is economically unattractive because of the formation of water-insoluble fluoroberyUates. Formation of these fluorides precludes efficient recovery of the unreduced beryUium from the reaction products in subsequent processing operations. 

Silver alone on a support does not give rise to a good catalyst (150). However, addition of minor amounts of promoter enhance the activity and the selectivity of the catalyst, and improve its long-term stabiHty. Excess addition lowers the catalyst performance (151,152). Promoter formulations have been studied extensively in the chemical industry. The most commonly used promoters are alkaline-earth metals, such as calcium or barium, and alkaH metals such as cesium, mbidium, or potassium (153). Using these metals in conjunction with various counter anions, selectivities as high as 82—87% were reported. Precise information on commercial catalyst promoter formulations is proprietary (154—156). 

In lieu of utilizing calcium carbonate as the neutralizing agent, calcium hydroxide, barium hydroxide, barium chloride or other alkaline earth metal salt or hydroxide forming an insoluble Sulfate may be employed. 

Acid resistance This property is best appreciated when the glass structure is understood. Most enamel frits are complex alkali metal borosilicates and can be visualised as a network of Si04 tetrahedra and BO, triangular configurations containing alkali metals such as lithium, sodium and potassium or alkaline earth metals, especially calcium and barium, in the network interstices. 

Because barium is an alkaline earth metal, Ba(OH)2 dissociates almost completely in water to provide OH ions. 

Calcium, strontium, and barium are called the alkaline earth metals, because their earths —the old name for oxides—are basic (alkaline). The name alkaline earth metals is often extended to all the members of Group 2 (Table 14.4). 

The true alkaline earth metals—calcium, strontium, and barium—are obtained either by electrolysis or by reduction with aluminum in a version of the thermite process (see Fig. 6.8) ... 

The alkaline earth metals can be detected in burning compounds by the colors that they give to flames. Calcium burns orange-red, strontium crimson, and barium yellow-green. Fireworks are often made from their salts (typically nitrates and chlorates, because the anions then provide an additional supply of oxygen) together with magnesium powder. 

Although the first report of an organometallic compound of the heavier alkaline earth metals appeared near the beginning of the twentieth century,291 the RMX Grignard analogs of Ca, Sr, and Ba never fulfilled their promise as general-purpose synthetic reagents. More difficult to form, less thermally stable, and less selective in their reactions than their Mg counterparts, the literature data of the compounds was often contradictory, and many syntheses were irreproducible (see Calcium, Strontium, and Barium in COMC (1982)). 

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